306 SUMMARY OF CURRENT RESEARCHES RELATING TO 



terised by their resistance to acids, their solubility in pepsin, and their 

 affinity for stains. It is not known how they are formed. 



Epidermic Proliferations on a Whale.* — Herr W. Weltner de- 

 scribes the remarkable way in which the epidermis of Megaptera hoops 

 sends upgrowths into the (18) chambers formed in the shell of Goronula 

 diadema, — a cirripede which fastens on the whale's skin. He also notes 

 the wart-like epidermic elevations (characteristic of this whale), from 

 the middle of which one or two hairs may project. 



Structure of Pavement Epithelium.f — Carlo Foa has studied the 

 epithelium of foetal calves and of adult cattle, in order to investigate the 

 remarkable network and intercellular bridges in regard to which various 

 opinions have been held. He finds that in very young embryos closed 

 polygonal chambers lie between the epithelial cells. As development 

 proceeds, the lamellae which form the lateral walls of the chambers 

 become more and more attenuated, and the lines which indicate the 

 crossing-points of these lamellae more distinct. The result is to produce 

 the appearance of fine bridge-like threads connecting the cells together. 

 Between these threads spaces occur in which the nutritive fluids of the 

 tissue circulate. 



Structure of Nervous System.} — Prof. L. Edinger briefly discusses 

 the gradual development of our present knowledge of the nervous 

 Bystem. In the first place, comparative researches both on the vertebrate 

 and the invertebrate nervous system have clearly shown that the ganglion- 

 cells are invariably the essential elements, and that they always give rise 

 to the nerve-fibres. Modern research may be said to have become con- 

 centrated around three questions : — (1) The relation between nerves and 

 ganglion-cells ; (2) the minute structure of the ganglion-cells ; and (3) 

 the relation between the nerves arising from different cells. As to the 

 first point, Apathy's work has shown that fine fibrils, having a specific 

 colour reaction, penetrate from the nerves into the ganglion-cells. In 

 some cases Apathy has succeeded in demonstrating the existence, both in 

 the peripheral and in the central nervous system, of a fibrillar network 

 which probably constitutes the true conducting substance of the nervous 

 system. Thus, his work may be said to demonstrate anatomically the 

 fact, hitherto proved only by physiological reasoning, that the ganglion- 

 cells constitute the central organs of the nervous system. Again, Nissl 

 has shown that the fine granules which have long been known in ganglion- 

 cells have a very intimate connection with the life of the cells, and contain 

 the substances which are used up during active functioning. The granules 

 lie between the fibrilke, and change according to the state of activity of 

 the cell. 



Centrosome in Nerve-cells.§ — M. Charles Nelis has studied the 

 nerve-cells of the dog and rabbit, employing various methods of fixation 

 and coloration in the search for the centrosome. He obtained entirely 

 negative results in normal specimens, and believes that the centrosome 

 is normally absent in the nerve-cells of mammals. Animals infected 



* SB. Ges. Naturfreunde Berlin, 1899, pp. 102-3 (2 pis.). 

 t Arch. Mikr. Anat., lv. (1900) pp. 431-41 (1 pi.). 

 j Ber. Senckenberg. Naturf. Ges., 1899, pp. 10S-11. 

 § Bull. Acad. R. Belg , xii. (1899) pp. 715-34 (1 pi.). 



