36 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the adherence of the vitreous humour to the pecten. The pecten is 

 thus concerned in the production of the vitreous humour in the adult eye. 

 In development the pecten starts, as Bernd has shown, from a 

 mesodermic keel and an ectodermic primodium, which are intimately 

 associated. Both form fibrils, which go to the making of the em- 

 bryonic vitreous humour. The neuroglia of the pecten arises from 

 proliferations of both layers of the secondary optic vesicle. The vas- 

 cular supply of the pecten is very carefully described. The author's 

 results go to show that the pecten helps to form the vitreous humour 

 and is also nutritive. It probably assists in regulating pressure, and 

 may have other functions. 



Eye of Toad.* — D. Tretjakoff gives an account of the minute 

 structure of the front part of the eye of Bufo cinereus, with especial 

 reference to the margin of the pupil and the associated structures. He 

 connects some of the peculiarities with the toad's nocturnal habits, and 

 takes a comparative survey. The development of the eye in general is 

 briefly discussed. 



Nerve-endings in Crocodile. f — R. Hulanicka has studied the minute 

 structure of nerve-endings in Crocodilus niloticus and Alligator lucius, 

 and in so doing breaks almost new ground. She describes the free 

 nerve-endings on the palate : the tactile cells of the tongue, jaws, and 

 ventral surface ; the tactile papilla? of the scales ; the mucosa of the 

 tongue and the palate ; the tactile corpuscles ; and the taste-buds, which 

 contain special cells not previously detected. 



Nervous System of Ampiiioxus.J — H. L. Kutchin describes the 

 structure and distribution of the peripheral nerves of the rostrum, 

 the buccal region, the velum, the branchial region, and the area pos- 

 terior to the atriopore. Attention is also directed to the so-called 

 " spinal ganglia " of Dogiel, which are interpreted as artefacts, to the 

 structure of the dorsal nerves, to their sensory endings, and to the 

 ventral nerves. Very satisfactory figures are given. 



Degeneration of Nerve-cells in Embryonic Nerve-cord. § — A. 

 Weber calls attention to the occurrence of cellular degeneration in the 

 course of development. Some cells disappear, and others more useful 

 or more favoured take their place. He refers particularly to germina- 

 tive ceds which equip the internal wall of the medullary canal of the 

 embryo skate. After having produced a number of neuroblasts, the 

 elements in question mostly die and disappear. The degeneration goes 

 on without seeming to impair the karyokinetic activity, and it is in 

 trying to multiply still further that they die. What persists longest in 

 the moribund element is the attraction sphere with its radiations. The 

 import of this is discussed. 



* Zeitsehr. wiss. Zool.,cv. (19131 pp. 537-73 (1 pi. and 6 figs.), 



t Arch. Zool. Exper., liii. (1913) pp. 1-14 (3 pis.). 



t Proc. Auier. Acad., xlix. (1913) pp. 571-621 (8 pis.). 



§ A"at. Anzeig., xliv. (1913) pp. 356-G4 (1 pi.). 



