Review on the Development of Drought Tolerant Maize Genotypes in Iraq

Abstract Stress is any physiological, physical or chemical change that leads to disturbance and imbalance in the plant. Water stress is one of the most important environmental stresses affecting plant growth and production. It is also known as the lack of available water in the soil to be absorbed by the plant at a stage of its growth, or the inability of the plant. On the absorption of water even if it is naturally present in the root environment due to the force affecting the holding of water molecules, as it was described as the state in which the amount of water absorbed by the roots is less than the water lost through transpiration from the vegetative system, meaning that it is the state in which the effort The water content of the plant and the fullness of its cells is low to a degree that affects the conduct of vital and physiological processes. During the occurrence of water stress, as the term “drought” is not accurate in the sense used, but it is sometimes expressed as the phenomenon of water shortage as a result of climatic elements of multiple weather conditions, As for the agricultural concept of drought (Agricultural Drought), it is according to the growth and formation of the crop, and it is assumed that it begins when the ready water is drained from the root zone, plant goes through three stages: First stage increases the water loss and the transpiration process until it reaches a point where the amount of water lost by transpiration exceeds the amount of water absorbed by the roots. On the water balance between these two processes in adaptation, and when the water stress intensifies, the plant moves to the third stage, after which the plants lose a large part of the water through transpiration, the stomata are closed and the photosynthesis process stops. Therefore water stress (drought) alone is one of the most influential environmental stresses in reducing maize productivity, Therefore, the role of the plant breeder came through the implementation of breeding programs for hybridization and selection until it obtains a plant adapted to drought through the occurrence of morphological changes that make plants phenotypically adaptable to conditions of lack of water and includes an increase in root size and reduction of leaf area.

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Lateral Spread of Three Warm-season Turfgrass Species as Affected by Prior Summer Water Stress at Two Root Zone Depths

HortScience ◽

10.21273/hortsci.48.6.790 ◽

2013 ◽

Vol 48 (6) ◽

pp. 790-795 ◽

Cited By ~ 6

Author(s):

Kurt Steinke ◽

David R. Chalmers ◽

Richard H. White ◽

Charles H. Fontanier ◽

James C. Thomas ◽

...

Keyword(s):

Water Stress ◽

Water Conservation ◽

Cynodon Dactylon ◽

Root Zone ◽

Warm Season ◽

Water Shortage ◽

Lateral Spread ◽

Urban Landscapes ◽

Native Soil ◽

Four Blocks

As a result of increasing demand for potable water, local and national initiatives to conserve municipal water supplies have been implemented. Many of these initiatives focus on reducing irrigation of turfgrass in urban landscapes and may totally ban irrigation during periods of severe water shortage. Proper selection of adapted turfgrass species and cultivars is vital to long-term water conservation initiatives. Turfgrasses that can survive and recover from extended hot and dry periods under limited to no irrigation would best meet water conservation objectives. The present study was conducted to evaluate the recuperative potential of transplanted plugs of 24 commonly grown cultivars of three warm-season turfgrass species after incremental increases in water stress imposed by withholding all water for up to 60 days. A 2-year field study was conducted consisting of eight blocks containing 25 plots each. Each block was planted with one plot each of eight cultivars of bermudagrass (Cynodon dactylon sp.), seven cultivars of st. augustinegrass (Stenotaphrum secundatum sp.), and nine cultivars of zoysiagrass (five of Zoysia japonica sp. and four of Zoysia matrella sp.). Four blocks were planted on native soil with no restriction to rooting, whereas the other four had an effective root zone of only 10 cm of soil. Cup cutter plugs were collected at predetermined intervals, transported to College Station, TX, replanted, and grown under well-watered conditions. Measurements of the lateral spread of the plugs were taken every 10 to 14 days for the first 60 to 70 days after planting (DAP). The lateral spread of plugs collected after 0 days of summer dry-down (DSD) was greatest for bermudagrass, intermediate for st. augustinegrass, and lowest for zoysiagrass. In most cases there were no consistent differences between cultivars within a species. All species grown on the 10-cm deep root zone were unable to survive the 60-day period without water and died within the first 40 days. For each species, lateral spread was increasingly delayed or reduced with increasing DSD. Although all three species grown on native soil were able to survive and recover from a 60-day period without water, the bermudagrass cultivars had the most rapid recovery rates measured as lateral spread of transplanted plugs.

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Agricultural Drought Risk Assessment: A Spatial Analysis of Hazard, Exposure, and Vulnerability in Zacatecas, Mexico

Water ◽

10.3390/w13101431 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1431

Author(s):

David Ortega-Gaucin ◽

Jesús A. Ceballos-Tavares ◽

Alejandro Ordoñez Sánchez ◽

Heidy V. Castellano-Bahena

Keyword(s):

Risk Index ◽

Hazard Index ◽

Environmental Indicators ◽

The State ◽

Agricultural Drought ◽

Agricultural Activity ◽

Drought Risk ◽

Hazard Exposure ◽

The World ◽

Agricultural Drought Risk

Drought is one of the major threats to water and food security in many regions around the world. The present study focuses on the evaluation of agricultural drought risk from an integrated perspective, that is, emphasizing the combined role of hazard, exposure, and vulnerability to drought. For this purpose, we used the Mexican state of Zacatecas as a case study. This state is one of the most vulnerable to the adverse effects of agricultural drought in the country. The proposed method includes three stages: first, we analyzed the risk of agricultural drought at the municipal scale using the FAO Agricultural Stress Index System (ASIS) in its country version (Country-Level ASIS) and also determined a Drought Hazard Index (DHI). Subsequently, we conducted a municipal assessment of exposure and vulnerability to drought based on a set of socioeconomic and environmental indicators, which we combined using an analytical procedure to generate the Drought Exposure Index (DEI) and the Drought Vulnerability Index (DVI). Finally, we determined a Drought Risk Index (DRI) based on a weighted addition of the hazard, exposure, and vulnerability indices. Results showed that 32% of the state’s municipalities are at high and very high risk of agricultural drought; these municipalities are located mainly in the center and north of the state, where 75.8% of agriculture is rainfed, 63.6% of production units are located, and 67.4% of the state’s population depends on agricultural activity. These results are in general agreement with those obtained by other studies analyzing drought in the state of Zacatecas using different meteorological drought indices, and the results are also largely in line with official data on agricultural surfaces affected by drought in this state. The generated maps can help stakeholders and public policymakers to guide investments and actions aimed at reducing vulnerability to and risk of agricultural drought. The method described can also be applied to other Mexican states or adapted for use in other states or countries around the world.

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The state of soil microbiotes during sunflower growing with an herbicide of imidazolinone group

Helia ◽

10.1515/helia-2021-0005 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Natalia Kostyuchenko ◽

Viktor Lyakh ◽

Anatoliy Soroka

Keyword(s):

Species Diversity ◽

Rhizosphere Soil ◽

Root Zone ◽

General Trend ◽

The State ◽

Trophic Groups ◽

Herbicide Application ◽

Fold Reduction ◽

Specific Species ◽

Number Of Bacteria

Abstract The effects of various concentrations of herbicide Euro-Lightning Plus on the state of microbiota in the root zone of sunflower have been studied. Soil of plant rhizosphere and interrow soil after treatment with the herbicide at the doses of 1.2 and 2.5 l/ha were taken for the analysis at the end of sunflower growing season. Rhizosphere soil without herbicide application was used as a control. The herbicide was applied at the stage of 2–4 true leaves. The total number of bacteria in the rhizosphere of control plants was 12.82 million CFU/g of soil while in the rhizosphere and in the interrow soil after herbicide treatment with a dose of 2.5 l/ha it decreased by 1.4–1.5 times. A general trend of decline in number of the basic ecological and trophic groups of bacterial microorganisms with the increase in a dose of herbicide was established. Microbiological coefficients that reflect the functional activity of the microflora indicate changes in its biological activity under the influence of the herbicide Euro-Lightning Plus, which leads to deterioration in the agroecological state of the studied soils. It was also found that herbicide application resulted in a rearrangement of micromycete complexes in the root zone of sunflower which led to a two-fold reduction, compared to the control, of mycobiota species diversity and the formation of a specific species composition of mycocenoses. A greater genus and species diversity of fungi of the microflora in the rhizosphere of control plants, in comparison with the herbicide-treated soil, was revealed. A reduction in species diversity of the genus Penicillium from six species in the control to 1–2 species in the rhizosphere of experimental sunflower plants as well as the absence of rare saprophytic fungi species from the genera Acremonium, Verticillium, Trichoderma and Paecilomyces were noted.

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On the utility of land surface models for agricultural drought monitoring

Hydrology and Earth System Sciences ◽

10.5194/hess-16-3451-2012 ◽

2012 ◽

Vol 16 (9) ◽

pp. 3451-3460 ◽

Cited By ~ 42

Author(s):

W. T. Crow ◽

S. V. Kumar ◽

J. D. Bolten

Keyword(s):

Soil Moisture ◽

Land Surface ◽

Cross Correlation ◽

Root Zone ◽

Vegetation Indices ◽

Agricultural Drought ◽

Drought Monitoring ◽

Global Evaluation ◽

Land Surface Models ◽

Surface Models

Abstract. The lagged rank cross-correlation between model-derived root-zone soil moisture estimates and remotely sensed vegetation indices (VI) is examined between January 2000 and December 2010 to quantify the skill of various soil moisture models for agricultural drought monitoring. Examined modeling strategies range from a simple antecedent precipitation index to the application of modern land surface models (LSMs) based on complex water and energy balance formulations. A quasi-global evaluation of lagged VI/soil moisture cross-correlation suggests, when globally averaged across the entire annual cycle, soil moisture estimates obtained from complex LSMs provide little added skill (< 5% in relative terms) in anticipating variations in vegetation condition relative to a simplified water accounting procedure based solely on observed precipitation. However, larger amounts of added skill (5–15% in relative terms) can be identified when focusing exclusively on the extra-tropical growing season and/or utilizing soil moisture values acquired by averaging across a multi-model ensemble.

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How downstream sub-basins depend on upstream inflows to avoid scarcity: typology and global analysis of transboundary rivers

Hydrology and Earth System Sciences ◽

10.5194/hess-22-2795-2018 ◽

2018 ◽

Vol 22 (5) ◽

pp. 2795-2809 ◽

Cited By ~ 12

Author(s):

Hafsa Ahmed Munia ◽

Joseph H. A. Guillaume ◽

Naho Mirumachi ◽

Yoshihide Wada ◽

Matti Kummu

Keyword(s):

Water Stress ◽

Water Use ◽

Water Availability ◽

Water Scarcity ◽

Management Practices ◽

Global Analysis ◽

Water Shortage ◽

River Basins ◽

Analytical Framework ◽

Available Water

Abstract. Countries sharing river basins are often dependent upon water originating outside their boundaries; meaning that without that upstream water, water scarcity may occur with flow-on implications for water use and management. We develop a formalisation of this concept drawing on ideas about the transition between regimes from resilience literature, using water stress and water shortage as indicators of water scarcity. In our analytical framework, dependency occurs if water from upstream is needed to avoid scarcity. This can be diagnosed by comparing different types of water availability on which a sub-basin relies, in particular local runoff and upstream inflows. At the same time, possible upstream water withdrawals reduce available water downstream, influencing the latter water availability. By developing a framework of scarcity and dependency, we contribute to the understanding of transitions between system regimes. We apply our analytical framework to global transboundary river basins at the scale of sub-basin areas (SBAs). Our results show that 1175 million people live under water stress (42 % of the total transboundary population). Surprisingly, the majority (1150 million) of these currently suffer from stress only due to their own excessive water use and possible water from upstream does not have impact on the stress status – i.e. they are not yet dependent on upstream water to avoid stress – but could still impact on the intensity of the stress. At the same time, 386 million people (14 %) live in SBAs that can avoid stress owing to available water from upstream and have thus upstream dependency. In the case of water shortage, 306 million people (11 %) live in SBAs dependent on upstream water to avoid possible shortage. The identification of transitions between system regimes sheds light on how SBAs may be affected in the future, potentially contributing to further refined analysis of inter- and intrabasin hydro-political power relations and strategic planning of management practices in transboundary basins.

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THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF SUGAR CANE (SACCHARUM OFFICINARUM): A REVIEW

Experimental Agriculture ◽

10.1017/s0014479710000645 ◽

2011 ◽

Vol 47 (1) ◽

pp. 1-25 ◽

Cited By ~ 47

Author(s):

M. K. V. CARR ◽

J. W. KNOX

Keyword(s):

Water Stress ◽

Water Relations ◽

Sugar Cane ◽

Root Zone ◽

Water Productivity ◽

Crop Coefficient ◽

Saccharum Officinarum ◽

Irrigation Scheduling ◽

Background Information ◽

Technology Choice

SUMMARYThe results of research on the water relations and irrigation needs of sugar cane are collated and summarized in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the centres of production of sugar cane is followed by reviews of (1) crop development, including roots; (2) plant water relations; (3) crop water requirements; (4) water productivity; (5) irrigation systems and (6) irrigation scheduling. The majority of the recent research published in the international literature has been conducted in Australia and southern Africa. Leaf/stem extension is a more sensitive indicator of the onset of water stress than stomatal conductance or photosynthesis. Possible mechanisms by which cultivars differ in their responses to drought have been described. Roots extend in depth at rates of 5–18 mm d−1 reaching maximum depths of > 4 m in ca. 300 d providing there are no physical restrictions. The Penman-Monteith equation and the USWB Class A pan both give good estimates of reference crop evapotranspiration (ETo). The corresponding values for the crop coefficient (Kc) are 0.4 (initial stage), 1.25 (peak season) and 0.75 (drying off phase). On an annual basis, the total water-use (ETc) is in the range 1100–1800 mm, with peak daily rates of 6–15 mm d−1. There is a linear relationship between cane/sucrose yields and actual evapotranspiration (ETc) over the season, with slopes of about 100 (cane) and 13 (sugar) kg (ha mm)−1 (but variable). Water stress during tillering need not result in a loss in yield because of compensatory growth on re-watering. Water can be withheld prior to harvest for periods of time up to the equivalent of twice the depth of available water in the root zone. As alternatives to traditional furrow irrigation, drag-line sprinklers and centre pivots have several advantages, such as allowing the application of small quantities of water at frequent intervals. Drip irrigation should only be contemplated when there are well-organized management systems in place. Methods for scheduling irrigation are summarized and the reasons for their limited uptake considered. In conclusion, the ‘drivers for change’, including the need for improved environmental protection, influencing technology choice if irrigated sugar cane production is to be sustainable are summarized.

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AGRO-CLIMATIC SUITABILITY AND WATER REQUIREMENT FOR TANZANIA GUINEAGRASS CULTIVATION IN THE STATE OF CEARÁ

Revista Caatinga ◽

10.1590/1983-21252017v30n424rc ◽

2017 ◽

Vol 30 (4) ◽

pp. 1028-1038 ◽

Cited By ~ 1

Author(s):

NAILSON LIMA SANTOS LEMOS ◽

ANA CLARA RODRIGUES CAVALCANTE ◽

THIERES GEORGE FREIRE DA SILVA ◽

JOSÉ RICARDO MACEDO PEZZOPANE ◽

PATRÍCIA MENEZES SANTOS ◽

...

Keyword(s):

Sandy Soils ◽

Weather Conditions ◽

Climatic Conditions ◽

Water Requirement ◽

The State ◽

Climatic Suitability ◽

Irrigation Water Requirement ◽

Productive Potential ◽

Shallow Soils ◽

Water Holding

ABSTRACT This study aimed to define areas suitable, and the irrigation water requirement for, cultivation of Tanzania guineagrass in the state of Ceará, Brazil. Tanzania guineagrass yield was estimated by a mathematical model, which considers the crop actual evapotranspiration, resulting from the crop climatological water balance. The water requirement throughout the year was estimated for soils with a water holding capacity of 20 (shallow soils), 40 (sandy soils), 60 (soils with medium texture) and 100 mm (clay soils). The relative frequency of occurrence of monthly productions greater than 2,750 kg DM ha-1 month-1 was obtained for different areas in Ceará, representative of most of the state's economic mesoregions. Tanzania guineagrass annual yields in the state of Ceará were between 20,000-30,000 kg DM ha-1 year-1. During the rainy season, the productive potential varies with the economic mesoregion, which presents different climatic conditions. The state of Ceará is only suitable for the rainfed production of Tanzania guineagrass for 4 months each year, predominantly from February to May, while weather conditions do not favor the development of this grass in the remaining months.

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ESTUDO SOBRE A POSSIBILIDADE DE PRODUZIR BIOGÁS PROVENIENTE DE RESÍDUOS DA AGROPECUÁRIA NO ESTADO DO TOCANTINS

ENERGIA NA AGRICULTURA ◽

10.17224/energagric.2019v34n01p40-47 ◽

2019 ◽

Vol 34 (01) ◽

pp. 40-47

Author(s):

Anderson Labegalini De Campos ◽

Anderson De Oliveira Pereira ◽

Josenilda Guimarães Lopes ◽

Renê Faria De Araújo ◽

Ronaldo Pereira Lima

Keyword(s):

Biogas Production ◽

Agricultural Waste ◽

Weather Conditions ◽

Clean Energy ◽

Agricultural Residues ◽

The State ◽

Environmental Damage ◽

Energy Matrix ◽

The Social ◽

Social Environmental

ESTUDO SOBRE A POSSIBILIDADE DE PRODUZIR BIOGÁS PROVENIENTE DE RESÍDUOS DA AGROPECUÁRIA NO ESTADO DO TOCANTINS ANDERSON LABEGALINI DE CAMPOS1; ANDERSON DE OLIVEIRA PEREIRA2; JOSENILDA GUIMARÃES LOPES3; RENÊ FARIA DE ARAÚJO4 E RONALDO PEREIRA LIMA5 Mestrado de Agroenergia, Universidade Federal do Tocantins, Avenida NS 15, Quadra 109 Norte, Plano Diretor Norte (Prédio do Programa de Pós-Graduação em Agroenergia), CEP 77001-090, Palmas, Tocantins, Brasil. [email protected]; [email protected]; [email protected]; [email protected]; 5 [email protected] RESUMO: O Tocantins, entre os estados do Brasil, é um dos que possuem valores superiores em quantidade de rebanhos de gado de corte, e a bovinocultura de leite cresce de forma continuada, favorecida pelas condições climáticas. Em 2015, o estado produziu 8 milhões de bovinos e bubalinos, 296 mil suínos e 158,9 mil caprinos. As fronteiras socioeconômicas terão uma melhora significativa com a utilização de resíduos gerados na atividade rural para a geração de energia, assim como para a redução dos prejuízos ao meio ambiente, ocasionados pelos resíduos produzidos. Diante do exposto, o objetivo do presente trabalho foi avaliar o potencial de produção de biogás para a geração de energia, por meio da fermentação de resíduos oriundos da agricultura e pecuária do estado do Tocantins. A metodologia utilizada foi a revisão bibliográfica, a sistemática, a descritiva e a explicativa. Verificou-se, com este artigo, a relevância social, ambiental e econômica da inserção da energia produzida a partir dos resíduos agropecuários na Matriz Energética Brasileira. Ainda que tenham custos para instalar o sistema no Estado, a utilização de digestores fermentativos é uma alternativa para diminuir os problemas com a destinação inadequada dos resíduos agropecuários, além de ser uma forma de energia limpa, este método possuí uma fonte de recursos com o comercio dos créditos de carbono, devido a não emissão do gás metano. Palavras-chave: resíduos agropecuários, energia, biogás. STUDY ON THE POSSIBILITY OF BIOGAS PRODUCING FROM AGRICULTURAL WASTE THE STATE OF TOCANTINS ABSTRACT: Beef and dairy cattle growing is one of the biggest production in the State of Tocantins - Brazil, favored by weather conditions. In 2015, the state produced 8 million cattle and buffalo, 296,000 pigs and 158,900 goats. The socioeconomic boundaries will have a significant improvement with the use of waste generated in rural activity for the generation of energy, as well as the reduction of environmental damage caused by the waste produced. Given the above, the objective of the present work was to evaluate the potential of biogas production for energy generation, through the fermentation of residues from the Tocantins state agriculture and livestock. The methodology used was the literature review, the systematic, the descriptive and the explanatory. This article verified the social, environmental and economic relevance of the insertion of energy produced from agricultural residues in the Brazilian Energy Matrix. Although they have costs to install the system in the state, the use of fermentative digesters is an alternative to reduce the problems with the improper disposal of agricultural residues, besides being a form of clean energy, this method has a source of resources with the trade. carbon credits due to non-emission of methane gas. Keywords: agricultural residues, energy, biogas.

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The State of the Hemomycocirculatory Bed of Adventitia of Varicose Veins of the Small Pelvis in Women with Chronic Inflammatory Diseases of the Internal Genital Organs

Archive of Clinical Medicine ◽

10.21802/acm.2017.2.6 ◽

2017 ◽

Vol 23 (2) ◽

Author(s):

Natalya Drohomyretska

Keyword(s):

Inflammatory Diseases ◽

Varicose Veins ◽

Morphological Changes ◽

Complex Structure ◽

The State ◽

Reproductive Age ◽

Ovarian Vein ◽

Women Of Reproductive Age ◽

Vein Wall ◽

Inflammatory Processes

Hemomicrocirculatory system – is a complex structure that reacts in every pathological process even before the clinical period and takes the first blow. The study of microhemocirculation will provide an opportunity to solve the important for practical medicine questions of pathogenesis of many diseases, as for the prevention and treatment of regional disorders of blood circulation.The objective of the research is to study the state of the hemomicrocirculatory bed (HMCB) of adventitia of varicose veins of the small pelvis (VVSP) in women with chronic inflammatory processes of the organs of the small pelvis (CIPOSP).Materials and methods of research. To evaluate the restructuring of the HMCB of adventitia of VVSP, the operating material of 12 women of reproductive age was used. Mainly, there were pieces of the ovarian vein. The study of the HMCB in the vein wall was performed by the non-injecting method of silver impregnation according to V.V. Kupriyanov. To standardize the results, the condition of the HMCB of adventitia of the venous wall in norm was studied in 5 women of reproductive age, who died as a result of various traumas.Results of the research. After the performed studies, the structural-morphological changes of the HMCB of the adventitia of the small pelvis veins were revealed. The dilation of capillaries, postcapillaries, postcapillary venules was observed. The diameter of the vessels of the HMCB of the ovarian vein adventitia was: venule – 94.21 ± 1.38 μM in comparison with the norm – 48.78 ± 1.60 μM (p<0.001); post-capillary venules – 46.76 ± 1.04 μM in comparison with the norm – 28.29 ± 1.1.01 μM (p<0.001); the capillaries were 11.22 ± 0.14 μM in comparison with the norm – 8.24 ± 0.16 μM (p<0.05), arterioles – 29.02 ± 0.76 μM in comparison with the norm – 25.19 ± 1.15 μM (p<0.01). The architectonics of the arterioles is almost unchanged. Lumen of venules is filled with formed elements. The structure of capillaries is polymorphic. The capillary net was localized and concentrated or was formed as a thick planar net, the capillaries were expanded. There were arterio-venulous anastomoses. Endothelial nuclei are shortened. In some preparations, the diameter of the arterioles corresponded to the diameter of the collection venules. Conclusions:1. The first discovered by us changes in HMCB of adventitia of varicose veins of the small pelvis in women with CIPOSP can be one of the pathogenetic links of the development and progression of the varicose vein itself, which in turn aggravates the course of chronic inflammation. 2. The timely appointment of drugs that improve microcirculation will enable to prevent the development of dystrophic changes in the vein wall, improve the course of chronic inflammatory processes and reduce or completely eliminate the syndrome of “chronic pelvic pain”.

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XVIII. On rubian and its products of decomposition

Philosophical Transactions of the Royal Society of London ◽

10.1098/rstl.1851.0021 ◽

1851 ◽

Vol 141 ◽

pp. 433-459 ◽

Cited By ~ 1

Keyword(s):

Chemical Change ◽

The State ◽

Common Origin ◽

Yellow Colour ◽

Atmospheric Air ◽

Indigo Blue ◽

The Subject ◽

The Many ◽

Do So ◽

Madder Root

Among the many discussions to which the subject of madder has given rise among chemists, there is none which is calculated to excite so much interest as that concerning the state in which the colouring matter originally exists in this root, and there is no part of this extensive subject which is at the same time involved in such obscurity. It is a well-known fact that the madder root is not well adapted for the purposes of dyeing until it has attained a growth of from eighteen months to three years, and that after being gathered and dried it gradually improves for several years, after which it again deteriorates. During the time when left to itself, especially if in a state of powder, it increases in weight and bulk, in consequence probably of absorption of moisture from the air, and some chemical change is effected, which, though not attended by any striking phenomena, is sufficiently well indicated by its results. There are few chemical investigations that have thrown any light on the nature of the process which takes place during this lapse of time, and in fact most of the attempts to do so have merely consisted of arguments based on analogy. It has been surmised that the process is one of oxidation, and that the access of atmospheric air is consequently necessary. We are indeed acquainted with cases, in which substances of well-defined character and perfectly colourless, as for instance orcine and hematoxyline, are converted by the action of oxygen, or oxygen and alkalies combined, into true colouring matters. A more general supposition is, that the process is one of fermentation, attended perhaps by oxidation, and in confirmation of this view the formation of indigo-blue from a colourless plant, by a process which has all the characters of one of fermentation, may be adduced. What the substance is however on which this process of oxidation or fermentation takes effect, what the products are which are formed by it, whether indeed the change is completed as soon as the madder has reached the point when it is best adapted for dyeing, or whether further changes take place when it is mixed with water and the temperature raised during the process of dyeing, are questions which have never been satisfactorily answered, if answered at all. It has indeed been suspected by several chemists, that there exists originally some substance in madder, which by the action of fermentation or oxidation is decomposed and gives rise by its decomposition to the various substances endowed either with a red or yellow colour, which have been discovered during the chemical investigations of this root. That several of these substances are merely mixtures, and some of them in the main identical, has been satisfactorily proved by late investigators. But there still remain a number, which, though extremely similar, have properties sufficiently marked to entitle them to be considered as distinct. In my papers on the colouring matters of madder, I have described four substances derived from madder, only one of which is a true colouring matter, but all of them capable, under certain circumstances, as for instance in combination with alkalies, of developing red or purple colours of various intensity. To seek for a common origin for these various bodies so similar to one another and yet distinct, is very natural, and the discovery of it no improbable achievement.

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