The control of stomatal aperture by intensity of light, under normal conditions of water-relations of surrounding cells, has apparently been established by Nutman (1937) for coffee leaves. This control results in the closing of stomatal pores both with too little and with too much illumination. Since photosynthesis in the guard-cells is not known to decrease with increase in light intensity, up to the limit of full sunshine, some other factor or factors are suggested as coming into action.

Investigations, in the Department of Botany, Queen's University, Belfast, by three research students have progressively elucidated some of the factors concerned.

Numerous investigations have already been made on the biology of Calanus finmarchicus. The main body of data, however, has been derived from field observations, and while many and important conclusions have been drawn from such work, confirmation of some of them is required by direct experimental methods. Accurate studies on the feeding, metabolism, and breeding of Calanus can only be made on living animals in the laboratory. Some such investigations have already been made by Crawshay, Clarke, Fuller, Marshall, Nicholls and Orr, Harvey and others, but the results have sometimes been obscure owing to the difficulties encountered in keeping Calanus in really healthy condition.

In the course of our studies of reproduction of Calanus finmarchicus under laboratory conditions we noticed that all the eggs produced in our cultures were lying on the bottom of the glass dishes, and when transferred into fresh culture medium (“Erdschreiber”) or sea-water sank down relatively very rapidly. As the eggs were fertilised and healthy, and a large proportion of them developed into active nauplii (Raymont and Gross, 1942), it was obvious that the density of the living egg was considerably higher than that of sea-water.

Stadler and Sprague in a series of papers (1936) succeeded in demonstrating by a genetical method the effect of ultra-violet radiation in maize pollen, and found that in their experiments in the X-ray series the chromosomal changes are very common, while in the ultra-violet series they are rare.

Until a few years ago the small size of the chromosomes limited the methods which could be used for their physical and chemical study. The discovery in 1933 that the salivary gland nuclei of Diptera contained giant multiple or polytene chromosomes threw the field open to the application of a variety of new techniques.

In recent years considerable progress has been made in the investigation of the biochemistry and physiology of the root nodules of leguminous plants (Wilson, 1940). It now appears desirable that the anatomical structure of the nodule should be re-examined from the standpoint of the functions which the nodule is considered to discharge. Special interest attaches to the distribution within the nodule of endodermis, cork, and any other suberized layers, since on this will depend the facility with which materials may be exchanged between the tissues of the nodule and the environment. There is some confusion in the literature as to the distribution of such suberized tissues within the nodule, but it is clear that rather curious features are presented.

It is well known that the dimensions of the ammonite shell conform approximately with the properties of a logarithmic or equiangular spiral. An illuminating account of the logarithmic spiral in its application to the growth of molluscan shells is that given by Sir D'Arcy Thompson (1917, pp. 491–586, and 1942, pp. 748–849). His formula relating the spiral angle of the shell and the ratios of certain linear dimensions must be useful to all interested in shell form in molluscs.

In 1930 ovulation in ferrets outside the breeding season was obtained by Hill and Parkes (1930) by means of gonadotrophic extracts. Later, similar results were obtained in sheep and thus it became possible to induce pregnancy outside the normal breeding season (Cole and Miller, 1933), and its practical importance was investigated by Parkes and Hammond (1940). Similar experiments on the golden hamster, Cricetus auratus, are described below, as this animal has proved to be a most interesting subject for the study of sex hormones (Klein, 1937 and 1938; Peczenik, 1942).