180 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the head and upper cervical vertebrae chiefly dependent on muscuhis 

 biventer and muscuhis spinahs. The head shifts from the normal egg 

 position of flexed lateral rotation to one of extension more nearly on 

 the vertebral axis. The reflex mechanism which touches off the muscles 

 referred to is probably a respiratory reflex (drinking-choking reflex), 

 not dependent on demand for oxygen, but dependent on distention of 

 the abdomen, particularly the muscuhis levator ani, brought about 

 through injection of the yolk-sac. The enormous lymph infiltration is 

 a result of rapid absorption, partly due to pressure and partly due to- 

 awakened glandular activity, as positive factors, and to th^ failure of 

 the kidneys to deal with the excess of water, as a negative factor.. 

 Not until respiration sets in does the general oedema disappear, which 

 implies that most of the water in birds is excreted by the lungs, and 

 also accounts for the ability of the newly-hatched chick to go at least 

 three days (perhaps four or five) without water. J. A. T. 



Hypertrophy of Suprarenal Capsules in Pregnant Rabbit. — 

 J. Watrin (g. E. Soc. Biol, 1919, 82, 14-.05-7). The hypertrophy 

 and increased functioning of the suprarenal capsule during pregnancy 

 has been referred by some to the influence of the foetus, whose waste - 

 products require additional anti-toxins to counteract them. But the 

 hypertrophy is seen also in the thyroid and in the hypophysis, which, 

 the author says, are not known to have an anti-toxic function. On his 

 view the hypertrophy of the suprarenal capsules is a reaction to specific 

 substances secreted by the ovum before its fixation and by elements in 

 the foetal part of the placenta. Moreover, this reaction does not come 

 about unless the suprarenal capsules have been " sensibilised " by the 

 internal secretion of the corpus luteum. J. A. T. 



Nutrition of Mammalian Foetus from Maternal Blood. — Hassan 

 EL Diw^ANY {G. R. Soc. Biol., 1919, 82, 1235-7). Maternal haemorrhage 

 in the placenta at a definite time during the gestation has been studied 

 in sheep, ferret, dog, cat, and white mouse. In the first four numerous 

 chorionic villosities enter the hagmorrhagic mass and numerous maternal 

 blood-corpuscles are captured by phagocytosis. Free maternal haemo- 

 globin is also observed. The chorion cells show biliary pigments in 

 their supra-nuclear portion and fatty droplets towards the base. In the 

 white mouse, cells of the trophoblast degenerate in the midst of the 

 extravasated red blood-corpuscles, and giant decidual cells act as the 

 phagocytes. These giant cells degenerate in turn and their debris is 

 absorbed by the high cylindrical cells Avhich form the visceral wall of 

 the l)lastodermic vesicle. The " hivmatic cmbryotrophy," the nutrition 

 from maternal blood, gives the foetus an abundant supply of iron. 



J. A. T. 



Testicular Epithelium.— Ed. Retterer {G. JR. Soc. Biol., 1919, 

 82, lir);]-G). In the human embryo and in the child the epithelium 

 of the testis is in cords, in the centre of which lacunas gradually appear, 

 making a tubule. In the middle of a syncytium of granular cells large 

 spermatocytes appear with clear perinuclear cytoplasm. Each gives 



