ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 23 



In Amphioxus a section of the cord shows the ependyma-cells sur- 

 rounding the central canal and continued into processes which form the 

 supporting fibres of the cord. The peculiarity of the supporting substance 

 consists not in the presence of these radially branching ependyma-cells, 

 but in the fact that the overwhelming majority of the supporting cells 

 have their cell-bodies placed on the central canal. The prolongations 

 of these cells in part correspond to the ependyma-cells of higher Verte- 

 brates, in part to the " glia " of these animals. In Myxine both epen- 

 dyma-cells and glia-cells are present. The former show much general 

 resemblance to those of Amphioxus. Careful examination of the neuro- 

 glia shows that it consists of fibrils having the same relation to the glia- 

 cells as the ependyma-cells to their fibrils. In general the supporting 

 tissue of the spioal cord of Myxine is a finely cellular tissue whose cells 

 are characterised by the staining reactions of their outgrowths, and in 

 certain places by their epithelial arrangement. A point of great interest 

 is the similarity in arrangement between the glia elements and the ner- 

 vous elements. Though the study of the neuroglia in the higher Ver- 

 tebrates is much more difficult, yet the results are sufficient to show a 

 general structural resemblance to the conditions seen in the lower. 



The most general conclusions from these results are : — (1) that the 

 most striking peculiarity of the neuroglia is the structural differentia- 

 tion between its fibrils and the cells from which the fibrils originate ; 

 and (2) that the neuroglia forms a tissue transitional between a purely 

 epithelial tissue and connective-tissue. 



Cortical Cells of Cerebellum.* — Herr Bjarne Eide, by the use of 

 the formol-chrome-silver method, has succeeded in staining the small 

 cells of the molecular layer of the cerebellar cortex in the cat; so as to 

 render possible the study of these little-known cells. He finds that 

 the " small " cells are of three kinds :— (a) cells of the ordinary second 

 type with short processes; (6) cells with long transversely arrauged 

 processes of remarkable structure ; (c) transitional forms. In (b) the 

 processes arise from the cell-body, or from a protoplasmic continuation 

 of the cell, and almost at once break up into numerous branches 

 (Anfangsverastelung). This is eminently characteristic of the cells, 

 and distinguishes them at once from the basket-cells of the molecular 

 layer. The cell-processes (axones) of the two kinds of cell are further 

 distinguished by the fact that in the basket-cells the axis-cylinder is 

 thick, in the small cells very thin. The axones also show a slight 

 difference in position, those of the basket-cells being more deeply placed ; 

 the varicose appearance of those of the small cells is also distinctive. 

 The two kinds resemble one another especially in that both ramify in 

 a transverse plane, and in that their ascending branches ultimately end 

 in both cases freely in the molecular layer. 



Multiple Division of Nerve-fibres.f — Prof. E. Ballowitz discusses 

 the multiple ("polytome"), brush-like or comb-like, division of medul- 

 lary nerve-fibres which R. Wagner described in 1847 in the electric nerves 

 of Torpedo. He has found a similar multiple division in Malopierurus, 

 where the nerve enters the electric tissue, but it is not so marked as iu 



* Zeitschr. f. wiss. Zool., lxvi. (1899) pp. 687-52 (14 figs). 

 T Anat. Anzeig., xvi. (1899) pp. 511-0 (2 figs.). 



