SUMMARY OF CURRENT RESEARCHES. 699 



during development become elongated, so that ependyma fibres run 

 obliquely in its neck. The body of the lobe consists of ependyma and 

 neuroglia cells and fibres ; no true nerve-cells are present in it, and there 

 is very little connective-tissue. The posterior lobe of the pituitary is, 

 from the first, a composite structure of epithelium of the pars intermedia 

 and of neuroglia aud ependyma, and the relations between the two 

 tissues become more and more intimate. Its vascular supply is derived 

 from a different source from that of the anterior lobe ; blood-vessels 

 grow into it at its posterior-superior angle, and form the capillaries in 

 the lobe. 



The intimate nature of the connection between the wall of Ratke's 

 pouch and the cerebral vesicle, and the maintenance of a close re- 

 lationship between the cells of the pars intermedia and the cerebro- 

 spinal canal, render it probable that the pituitary body of Mammalia is 

 to be regarded as the representative of an old mouth opening into the 

 canal of the central nervous system. Such an arrangement exists in its 

 simplest form in the Ascidian larva. A connection between Ratke's 

 pouch or original mouth-cavity and the interior of the infundibulum is 

 sometimes seen in the developing cat, and in the adult cat it is not 

 uncommon to find epithelial cells, derived from the buccal cavity, lying 

 inside the posterior lobe, in communication with the third ventricle of 

 the brain. 



The anterior lobe proper is a gland whose secretion must enter the 

 blood directly, and so pass into the general circulation. The pars inter- 

 media, on the other hand, appears to secrete into the brain tissue, and 

 must be regarded as a brain gland. The nature of these secretions, and 

 the question as to whether that of the pars intermedia is modified by 

 its passage through brain-substance, await further investigation. 



Orientation of Embryo in Hen's Egg.*— E. Rabaud finds that 

 there is for every embryo a fixed orientation, at least during the first 

 few days of development ; that the mobility of the yolk does not allow 

 of any rotation ; and that there is never more than oscillation. During 

 the first five or six days, at least, the position of the yolk remains 

 practically fixed. 



Apparent Anomalies in Mendelian Proportions.! — L. Cuenot con- 

 siders a number of experiments in mice-breeding, where the numerical 

 results do not at first sight seem to agree with Mendelian expectations, 

 and shows that they are not difficult to explain. He maintains con- 

 fidently that all the determinants known in mice illustrate Mendelian 

 inheritance. 



Inheritance in Canaries. J — Charles B. Davenport has made ob- 

 servations on inheritance in domestic canaries, and shows that distinctive 

 characters which have arisen during the 250 years or so of its controlled 

 breeding (a short time compared with the 2000 years or more during 

 which poultry have been bred) behave in Mendelian fashion. 



Crest is dominant over plain head. Baldness is a unit-character and 



* Arch. Zool. Exper., ix. (1908) Notes et Revue, No. 1, pp. i.-vi. 



t Tom. cit., pp. vii.-xv. 



X Publications of Carnegie Institution of Washington, 1908, pp. 1-26 (3 pis.). 



3 a 2 



