scholarly journals A further note on the nutrition of the early embryo: with special reference to the chick

1908 ◽  
Vol 80 (540) ◽  
pp. 332-338 ◽  
Keyword(s):  
Special Reference ◽  
Royal Society ◽  
Early Embryo ◽  
Accurate Analysis ◽  
Preliminary Note ◽  
Series Of Experiments ◽  
Uterine Secretion ◽  
Do So

In furtherance of the views put forward regarding the nutrition of the early embryo by the author in a preliminary note read before the Royal Society in February, 1905, the following series of experiments was carried out. The changes that take place between the growing embryo and the maternal secretion are in the mammalia, not easy to study, on account of the difficulties to be encountered, such as the minute size of the embryo, and the small amount of uterine secretion available. In birds, on the order hand, the uterine secretion, viz., the white of the egg, is abundant. The growing embryo can be examined easily at any stage which may be desired, and since all the changes which take place do so within the limits of the shell, the products of these changes are capable of accurate analysis.

scholarly journals A preliminary note upon the question of the nutrition of the early embryo, with special reference to the guinea-pig and man

1905 ◽  
Vol 76 (508) ◽  
pp. 164-165 ◽  
Keyword(s):  
Guinea Pig ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Early Embryo ◽  
Uterine Horn ◽  
Dense Layer ◽  
Preliminary Note ◽  
Trophoblastic Cells ◽  
Decidual Cells ◽  
Uterine Secretion

During the progress of a research into the earliest implantation of the embryo of the guinea-pig, I have been particularly struck with the way in which the nutrition of the embryo is anticipated and provided for during the time it remains free in the uterine horn. The so-called yolk-granules of the ovum are obviously insufficient to provide for the growth of the embryo to the stage prior to differentiation of the inner cell-mass, to which it attains during the five or six days which elapse before it comes into contact with the maternal tissues. It is clear that it must derive nourishment from the medium in which it lies―the product of the secretion of the uterine or other glands, which, during the period of pro-œstrum, exhibit such marked activity. I suggest that this secretion, which consists of mucus and probably albumin, is assimilated by the embryo after having undergone a process of digestion, the result of a secretory activity on the part of the outermost cells of the embryo―the cells of the Trophoblast. This suggestion I base on my observations in the guinea-pig, where I am able to demonstrate a breaking-down of maternal cells before the Trophoblastic cells are in actual contact; likewise in human placentation where a more or less dense layer of fibrin and broken-down leucocytes and decidual cells, the result of Trophoblastic activity, affords a barrier interposed between the invading Trophoblastic cells and the Decidua. This layer I purpose naming the “Protective Layer.” Looked at from a comparative point of view, there is in all probability a close analogy between the uterine secretion of mammals, and the secretion of the oviducts of the lower vertebrata. In the case of birds the analogy is very striking, on account of the direct and important share in the nutrition of the embryo afforded by this secretion, commonly known as the white of the egg. In the case of the frog the ovum receives in its passage down the oviduct, corresponding to the uterine horn of the guinea-pig, a coating of mucus and probably albumin, comparable to the uterine secretion referred to above; when it reaches the water and becomes fertilised, this swells up by absorption, forming a gelatinous covering. The embryo for nutriment depends upon the yolk contained in the ovum before fertilisation, upon the covering of mucus and probably albumin, and lastly upon the water in which it lies. In certain mammals, as, for example, the rabbit and the mole, a distinct gelatinous envelope is described as surrounding the embryo before implantation occurs; this envelope is, I suggest, possibly due to some digestive action of the cells of the Trophoblast upon the adjacent medium, producing a form of coagulation.

scholarly journals I. Theory of magnetism based upon new experimental researches

1883 ◽  
Vol 35 (224-226) ◽  
pp. 178-202 ◽  
Keyword(s):  
Molecular Structure ◽  
Royal Society ◽  
Preliminary Note ◽  
Series Of Experiments ◽  
Experimental Researches

In a preliminary note I communicated to the Royal Society the formulated results of a lengthened series of experiments with the induction balance, and I now present the experimental evidences which led me to these conclusions. From numerous researches previously made by means of the induction balance, the results of which I have already published, I felt convinced that in researches upon the cause of magnetism, I should have in it the aid of the most powerful instrument of research ever brought to bear upon the molecular construction of iron, as indeed of all metals. It neglects all forces which do not produce a change in the molecular structure, and enables us to penetrate at once to the interior of a magnet or piece of iron, observing only its peculiar structure and the change which takes place during magnetisation or apparent neutrality.

III. On the thickness of soap films

1878 ◽  
Vol 26 (179-184) ◽  
pp. 334-345 ◽  
Keyword(s):  
Electric Current ◽  
Royal Society ◽  
Liquid Films ◽  
Soap Films ◽  
Preliminary Note ◽  
Series Of Experiments ◽  
The Law ◽  
Molecular Attraction

Attempts have from time to time been made by various physicists obtain from the phenomena of capillarity, or from observations on liquid films, an indication of the magnitude of the radius of molecular attraction. The authors of this note have, with the same object in view lately made a series of experiments to determine whether the law that the resistance offered to the electric current by a uniformly thick homogenous body varies inversely as the section is or is not apparent obeyed by liquid films, as any apparent departure from that law might be taken to indicate a want of homogeneity, or that the thickness of the film was comparable with the magnitude of the radius of molecular attraction. Their investigations on this point are not as yet sufficiently advanced for publication; but in the course of their work they have made some observations on the forms of soap films, which they venture to lay before the Royal Society in a preliminary note.

scholarly journals XIV. On the absorption of gases by solids

1881 ◽  
Vol 32 (212-215) ◽  
pp. 407-408
Keyword(s):  
Royal Society ◽  
Hydraulic Press ◽  
Careful Examination ◽  
Solid Matter ◽  
Chemical Action ◽  
High Pressure And Temperature ◽  
Solid Iron ◽  
Series Of Experiments ◽  
The Subject ◽  
Very High

During the progress of the investigations which I have from time to time had the honour of bringing under the notice of the Royal Society, I have again and again noticed the apparent disappearance of gases inclosed in vessels of various materials when the disappearance could not be accounted for upon the assumption of ordinary leakage. After a careful examination of the subject I found that the solids absorbed or dissolved the gases, giving rise to a striking example of the fixation of a gas in a solid without chemical action. In carrying out that most troublesome investigation, the crystalline separation of carbon from its compounds, the tubes used for experiment have been in nine cases out of ten found to be empty on opening them, and in most cases a careful testing by hydraulic press showed no leakage. The gases seemed to go through the solid iron, although it was 2 inches thick. A series of experiments with various linings were tried. The tube was electro-plated with copper, silver, and gold, but with no greater success. Siliceous linings were tried fusible enamels and glass—but still the' tubes refused to hold the contents. Out of thirty-four experiments made since my last results were published, only four contained any liquid or condensed gaseous matter after the furnacing. I became convinced that the solid matter at the very high pressure and temperature used must be pervious to gases.

W. T. Astbury and Ross G. Harrison: the search for the molecular determination of form in the developing embryo

1980 ◽  
Vol 35 (2) ◽  
pp. 195-219 ◽  
Keyword(s):  
Royal Society ◽  
Limb Bud ◽  
Amphibian Embryo ◽  
X Ray ◽  
Biological Phenomena ◽  
Biology I ◽  
Series Of Experiments ◽  
Molecular Patterns ◽  
Molecular Determination

Amongst the Fellows elected to the Royal Society in 1941 were W. T. Astbury for his studies using X-ray analysis to study the structures of natural fibres, and amongst the Foreign Members elected that year was Ross G. Harrison for his contributions to embryology. Astbury and Harrison were very different in temperament, and worked in very different fields on either side of the Atlantic, yet they were united in their approach to the study of biological phenomena. Both Astbury and Harrison believed that the organization and form of biological materials whether wool fibres or the limb-bud in an amphibian embryo depended on molecular structure and pattern. Moreover both were concerned with dynamic aspects of form; Astbury’s greatest achievement was to demonstrate the dynamic, reversible folding and stretching of proteins in the k-m-e-f group, and Harrison looked to changing molecular patterns to account for changing symmetries in the developing embryo. It was this common approach that brought them together and led to Harrison spending a brief month in Leeds where they and K. M. Rudall performed what have been described as ‘truly progressive experiments in molecular biology’. I believe this short series of experiments illuminates the character and work of both Harrison and Astbury and illustrates the difficulties, practical and conceptual, in carrying out ‘progressive experiments’. I shall begin by reviewing briefly the embryological background of the time before going on to discuss in detail the approaches of Harrison and Astbury to their work and the outcome of their collaboration.

The Estimation of the Efficiency of Sampling, with Special Reference to Sampling for Yield in Cereal Experiments

1935 ◽  
Vol 25 (4) ◽  
pp. 545-577 ◽  
Author(s):  
F. Yates ◽  
I. Zacopanay
Keyword(s):  
Standard Deviation ◽  
Special Reference ◽  
Analysis Of Variance ◽  
Sampling Methods ◽  
Cereal Crops ◽  
Loss Of Information ◽  
Preliminary Discussion ◽  
Experimental Errors ◽  
Series Of Experiments ◽  
The Mean

The estimation of the experimental yields of cereal crops by sampling methods is considered in the light of results of eighteen experiments which were harvested by these methods at Rothamsted and its associated centres. The harvesting results of the Crop-Weather series of experiments are also included.A preliminary discussion of the interpretation of the analysis of variance as applied to sampling results is given, and an expression is found for the loss of information arising out of sampling. The results of the discussion are applicable to all types of sampling carried out on replicated experiments.The sampling and experimental errors of all the experiments have been calculated. The variation between sampling units in the same subplot (usually between l/100th and l/200th acre) was found to be such as would arise if each metre length of row had a standard deviation (about the plot mean) of the order of 25–30 per cent. of the mean yield.

scholarly journals IX. On the structure and development of the liver

1849 ◽  
Vol 139 ◽  
pp. 109-137 ◽  
Keyword(s):  
Royal Society ◽  
A Priori ◽  
Structural Features ◽  
Structure And Function ◽  
Conclusive Evidence ◽  
Interesting Paper ◽  
Biliary Ducts ◽  
And Function ◽  
Do So

In venturing to offer a second communication to the Royal Society respecting the structure of the liver, I feel the rather anxious to do so, that I may have an opportunity of correcting an error and supplying a deficiency which existed in my previous paper. In the following observations I purpose to present some account of the structure of the liver examined in the ascending series of animals, and also to describe the several stages of its evolution in the embryo; in this way I trust I may be able to exhibit the characteristic structural features of the organ as it exists in Man and the higher animals, and also to determine the true place which ought to be assigned to it in a classification of the various glandular organs occurring in the same. I am not aware that any detailed account of the structure of the liver has been recently published, except that by M. Natalis Guillot, which however, so far as I comprehend it, does not seem to be one that can be readily accepted; the idea that the minute biliary ducts and lymphatics originate together in a common net-work, is à priori improbable, and entirely opposed to conclusive evidence (as I think), which will be subsequently adduced. A very interesting paper on the structure and function of the liver has also appeared in the 4th volume of the Guy’s Hospital Reports, from the pen of Dr. Williams; to his labours I shall several times have occasion to refer, but it will be seen that I differ from him in several particulars, especially respecting the importance of the basement or limitary membrane.

scholarly journals XXIV. Experiments and observations on the Newry pitch-stone, and its products, and on the formation of pumice

1822 ◽  
Vol 112 ◽  
pp. 313-338
Keyword(s):  
Royal Society ◽  
Vice Presidents ◽  
Geological Society ◽  
Do So

The locality of this mineral, and the singularity of its ex­ternal characters, having excited my curiosity, I took advan­tage of the facilities furnished by the liberality of the Royal Society of Dublin, of which I have the honour of being one of the Vice Presidents, to make the subjoined analysis in their laboratory. Doctor Fitton, in an excellent paper inserted in the first volume of the Transactions of the Geological Society, has given a minute description of the site and external characters of the Newry pitch-stone. I shall transcribe it, previous to laying before the Royal Society my own observations. I do so with more satisfaction, as we in general agree; in fact, scarcely two specimens are exactly the same, although contiguous to each other in the vein ; some being compact, some thin slaty, some olive, and some leek-green ; some so disin­tegrated, particularly when exposed to the air, as to be friable between the fingers, while others retain their gloss, consistency, and colour, with much tenacity, although they all fall at length into rhomboidal fragments. I may add also, that while some are quite porphyritic, others have but a few specks of felspar on their surface.

Intercellular communication in the early embryo of the ascidian Ciona intestinalis

Development ◽  
1988 ◽  
Vol 102 (1) ◽  
pp. 55-63 ◽  
Author(s):  
F. Serras ◽  
C. Baud ◽  
M. Moreau ◽  
P. Guerrier ◽  
J.A.M. Van den Biggelaar
Keyword(s):  
Intercellular Communication ◽  
Lucifer Yellow ◽  
Ciona Intestinalis ◽  
Early Embryo ◽  
Cell Stage ◽  
Early Embryos ◽  
Junctional Conductance ◽  
Voltage Dependent ◽  
Cytoplasmic Bridges ◽  
Series Of Experiments

We have studied the intercellular communication pathways in early embryos of the ascidian Ciona intestinalis. In two different series of experiments, we injected iontophoretically the dyes Lucifer Yellow and Fluorescein Complexon, and we analysed the spread of fluorescence to the neighbouring cells. We found that before the 32-cell stage no dye spread occurs between nonsister cells, whereas sister cells are dye-coupled, possibly via cytoplasmic bridges. After the 32-cell stage, dye spread occurs throughout the embryo. However, electrophysiological experiments showed that nonsister cells are ionically coupled before the 32-cell stage. We also found that at the 4-cell stage junctional conductance between nonsister cells is voltage dependent, which suggests that conductance is mediated by gap junctions in a way similar to that observed in other embryos.

Edgington on Possible Knowledge of Unknown Truth

2021 ◽  
pp. 195-211
Author(s):  
Timothy Williamson
Keyword(s):  
Special Reference ◽  
Truth Conditions ◽  
General Constraint ◽  
Counterfactual Conditionals ◽  
Counterfactual Situation ◽  
The Church ◽  
Do So

The chapter responds to Dorothy Edgington’s article ‘Possible Knowledge of Unknown Truth’, which defends her seminal diagnosis of the Church–Fitch refutation of verificationist knowability principles. Using counterfactual conditionals, she reformulates those principles to block that objection. The chapter argues that, to avoid trivialization, Edgington must supply a more general constraint on how the knower specifies a counterfactual situation for purposes of her reformulated principles; it is unclear how to do so. The philosophical motivation for her strategy is also questioned, with special reference to her treatment of Putnam’s epistemic account of truth. In passing, it is questioned how dangerous Church–Fitch arguments are for verificationist principles with non-factive evidential attitudes in place of knowledge. Finally, a doubt is raised about the compatibility of Edgington’s reformulation strategy with her view that counterfactual conditionals lack truth-conditions.

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