The kinetics of hœmoglobin VI -The competition of carbon monoxide and oxygen for hœmoglobin

The experimental part of the research to be described below is given in two main sections. Of these Section 1 deals with the results obtained in measurements of the rate of displacement of oxygen from combination with hœmoglobin by carbon monoxide. Section 2 gives, in corresponding fashion, the results for the reverse reaction, namely, the displacement of carbon monoxide from combination with hœmoglobin by oxygen. The theoretical aspects of theses two reactions have already been dealt with in broad outline at the end of Part IV, with which it will be assumed that the reader is fully acquainted. Some further considerations, however, arise and these are given in Section 3 of the present paper.

Induction of fertility and pregnancy in the anœstrous ferret

Bissonnett (1932) was able to induce complete œstrus in three female ferrets by evening illumination from October 12 onwards, but similar treatment of a male from October 12 to December 22 failed to carry spermatogenesis beyond the spermatocyte stage. Mating, therefore, resulted only in pseudopreganancy. In a second series of animals illuminated from December 7 onwards, spermatorgenesis was secured during February and a litter was born on April 11 (Bissonnette, 1933). The normal untreated male, however, usually becomes fertile during February (Allanson, 1932) and the first litters of the season may be born early in April, so that Bissonnette cannot be said to have induced fertility outside the limits of the normal breeding season. Bissonnette’s failure to bring about premature spermatogenesis, though involving one animal only, suggested that the male was much more refractory than the female, especially since anterior lobe extracts and urine of pregnancy extracts readily cause ovulation in the anœstrous ovary (Hill and Parkes, 1930), while such extracts cause little reaction in the quiescent winter testis. It seemed, however, that a combination of additional light and gonad-stimulating extracts might be effective, and the present paper records experiments carried out on these lines, as a result of which pregnancy was induced in light-treated females well outside the limits of the normal breeding season.

The habits and structure of pseudapocryptes lanceolatus, a fish in the first stages of structural adaptation to aerial respiration

Two short accounts of the habits of pseudapocryptes lanceolatus were communicated by me to the Indian Science Congress and were published in the Proceedings of the Congress, Das (1930), Das (1932). There are 11 Indian genera of the family Gobiidæ which include 89 species. The genus Pseudapocryptes has been reported from the coasts of India, Burma, the Andaman Islands, and the Malay archipelago. The specimens of pseudapocryptes lanceolatus studied were obtained from the estuary of the Ganges, Chiefly from Port Canning and Diamond Harbour, not far from Calcutta. The fish is often brought to the Calcutta market and is especially abundant during the months of October and November.

The projection of the forebrain on the pons and cerebellum

Although the existence of the cortico-pontine fibres has long been recognized and their functions partially elucidated in more recent times, there has as yet been no solution of the problem of their distribution in the pons and projection on the cerebellum. The thorough investigation of the problem requires prolonged and tedious experimental work and has, probably on that account, hitherto been largely neglected. But experiments are not performed only by man. In obscure recesses of the animal kingdom lie hidden experiments of Nature which, confined within the limits of the direction of evolution chosen for them, have been condemned to carry their eccentricity to its logical conclusion. Experiments of an even more casual nature have been performed by the indiscriminate invasion of every part of the human brain by pathological processes; but it is only by the patient collection and examination of vast masses of records that any continuous narrative can be extracted from the chaotic whole. Of the three types of experiment available it is more economical of time and material to chose that which comes ready-made: the method of comparative neurology. This, even if it does not supply a complete answer, at least provides valuable clues for the more accurate direction of the other methods.

The numbers of bacterial cells in field soils, as estimated by the ratio method

It has long been recognized that the method of counting bacteria in a soil sample by means of plate counts is valueless as an estimate of the total bacterial population, although such counts have undoubted value in comparing two or more samples. The numbers obtained by this method represent only a small fraction of the total population. This is due mainly to the fact that no single plating medium will enable all the diverse groups of soil bacteria to multiply and produce colonies. Indeed, many types will not grow on any of the media commonly used for plate counts, and it is very uncertain whether those which do so are of main importance in carrying out biochemical changes in the soil itself. The number of colonies which appear is probably reduced further by the fact that, in some soils, many of the bacteria occur in clumps which would not easily be broken up in the process of making the soil suspension. These limitations of the plate method make it very important that a technique should be developed for making accurate estimates of the total bacterial content of a soil sample from direct microscope counts. The counting of bacteria in dried and stained films has become a recognized technique for milk (Breed, 1911). A comparison between plate and direct microscope counts of milk samples was made by Breed and Stocking (1920) and more recently by Buice (1934) who found that the numbers obtained by two methods were of the same order. With milk, however, most, if not all, of the organisms counted were of types capable of growing upon the plating medium used. The application of direct counting methods to bacteria in a soil sample is greatly complicated by the presence of the soil particles. These introduce difficulties in staining the film, in obtaining an even distribution of bacteria over the film, and in estimating the mass of soil examined.

The kinetics of hæmoglobin VII—Some notes on the reactivity of freshly reduced hæmoglobin

Various results, which are anomalous from the theoretical point of view, have been described and discussed in our previous papers, notably in those dealing with the displacement of O 2 by CO from combination with hæmoglobin, and vice versa . The fact that these anomalies were specially found where dissociation of 1 molecule, e. g. , of O 2 from hæmoglobin is quickly followed by combination with another molecule ( e. g. , of CO), so that the group in the hæmoglobin molecule concerned only remains free for a very short time, suggested to us the possibility that such freshly formed and short lived groups might differ in reactivity from that of same groups, when allowed a longer period of life before meeting the second reactant. For the sake of brevity such freshly-formed and shortly-lived molecules will be referred to as "new" molecules, whilst the molecules with which they are to be contrasted in activity will be called "old".

The kinetics of hœmoglobin IV- General methods and theoretical basis for the reactions with carbon monoxide

Some years ago, Hartridge and Roughton published four papers (1923-1927) upon the kinetics of the rapid reactions between oxygen and hæmoglobin. Following on this work an investigation has been made of the corresponding reactions between carbon monoxide and hæmoglobin, and also of the reactions in which carbon monoxide and oxygen both compete for union with hæmoglobin. According to the classical paper of Douglas, Haldane and Haldane (1912) the hæmoglobin-carbon monoxide reactions should only differ from the hæmoglobin-oxygen reactions in the numerical value of the mass action constants. It was therefore expected that the kinetic study of these sister reactions would contribute towards a fuller understanding of these sister reactions would contribute towards a fuller understanding of the reactions between oxygen and hæmoglobin. Furthermore, a knowledge of rates of the carbon monoxide reactions is of service, not only in working out the factors involved in the passage of O 2 into the red blood corpuscle (Roughton, 1932), but also in interpreting the measurements of the carbon monoxide as a "physiological reagent," e. g. , determination of blood volume and distribution, indirect measurement of O 2 pressure in arterial blood, cool gas poisoning, etc. Lastly, the similarity between the kinetics of the reactions of O 2 and CO with hæmoglobin and the kinetics of numerous enzyme processes, as set forth especially by J. B. S. Haldane in his recent book (1930), makes this problem well worth working out from the viewpoint of enzyme chemistry.

The kinetics of hœmoglobin V- The combination of carbon monoxide with reduced hœmoglobin

The theoretical aspects and importance of this reaction have already been discussed in the introductory paper of this series (part IV) as have also the experimental methods in broad outline. It will be assumed here that the reader is familiar with the paper. In the present paper will be found the experimental results of the tests suggested in part IV, together with an account of the effect of pn and temperature on the rate of combination of carbon monoxide with reduced hæmoglobin. It will be useful to describe first of all the results of a typical experiment at pH 10, temperature 21º C, [CO] = 0·1 mM, [Hb] = 0·06m M. These are plotted in fig. 1. It will be seen that the reaction is half complete in about 0·05 second and there is therefore no doubt that the apparatus is amply adequate for coping with the reaction, since in our previous papers we have shown that even reactions more than ten times as fast could still be accurately measured.

The relative aetiological importance of birth order and maternal age in mongolism

Mongolian imbeciles are very often born last in a long family. The fact, which was pointed out many years ago by Shuttleworth (1909), has led clinicians to believe that mongolism is to believe that mongolism is to some extent a product of the exhaustion of maternal reproductive powers due to frequent child-bearing (Still, 1927; Fantham, 1925). The conclusion is widely accepted with the reservation that the affected child is not necessarily born at the end of the family (Thompson, 1925). Several cases are first-born, in fact, and it is sometimes stated that the condition occurs more frequently in first and last children than in other ordinal positions. There is, however, ample evidence that mongolian imbeciles have a significantly later birth rank than normal children (Hogben, 1931). It is also established, from large numbers of figures which have been collected, that the maternal age at the birth of mongolian imbeciles is unduly high. Though some of these imbeciles have young mothers, most of the cases (about 70%) are born after the mother has reached the age of 35 years. Thus the maternal age itself is likely to be an aetiological factor quite as important as birth order. I Know of no serious attempt, however, to distinguish between the aetiological significance of these two factors: to do this is the task I have umdertaken.

Hypophysectomy of birds. I-Technique, with a note a on results

Hypophysectomy is now performed readily in many mammals and amphibians, but so far it has apparently not been successfully accomplished in birds. Fischera (1905) attempted to cauterize the pituitary body of the fowl, but obtained only dubious results. In view of our increasing knowledge of the reproductive system and secondary sexual characters of birds, it is evident that hypophysectomy would open up a wide field of investigation for work on sex hormones. The parapharyngeal route for removing the pituitary was precluded by the large size of the gullet, while the temporal route seemed to offer little hope. The extensibility of the mouth tissues, however, suggested that a buccal approach would be practicable. It was found barely possible to open the beak sufficiently to give easy access to the back of the mouth, but a comparatively small incision in the thin elastic floor of the mouth provided a ready approach to the soft palate and the base of the skull. We have found it possible to remove the pituitary with comparative ease by this transbuccal route, and the present paper is devoted to a description of the exact technique of the operation. The following description applies primarily to the fowl; notes on the differences found in other birds are given in Section III.