ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 179 



but penetrate it from outside. Further, by subjecting the nerve-cells of 

 mammals to an induction current, be finds that the canaliculi become 

 dilated, and it can thus be demonstrated that the whole cell-body is 

 interpenetrated by an intricate network of canaliculi, of which those 

 previously observed are merely the wider portions. As to the ganglion- 

 cells of Lopliius, he finds that intracellular canaliculi carrying blood- 

 corpuscles are rare ; indeed, he is disposed to believe that the canaliculi- 

 containing capsular processes of the spinal neive-cells are analogous to 

 the intracellular caualiculi of the higher animals. 



In regard to the nerve-cells of Petromyzon, he thinks that Studnicka 

 is mistaken in supposing that the canaliculi there are produced by the 

 confluence of " alveoli " or vacuolar spaces ; on the contrary, they have 

 distinct walls staining red with toluidin-erythrosin. Otherwise his 

 observations agree with those of Studnicka. 



A study of Crustacean nerve-cells has revealed canaliculi in them 

 also, and there their lymphatic function and extracellular origin is 

 unmistakable. The wide distribution of these structures shows that the 

 nerve-cell is of much more complicated organisation than has hitherto 

 been supposed, and that current views on its characters require to be 

 greatly modified. 



Vascular Apparatus of Ganglion-cells.* — Prof. A. Adamkiewicz 

 recalls that in 1886 he maintained that a ganglion-cell, e.g. in the 

 intervertebral ganglia of the brachial plexus in man, has a vascular 

 system of its own. The arterial capillaries are continued into intra- 

 cellular capillaries of a second order, too minute, of course, to have 

 blood-corpuscles, but containing blood-serum. The veins also com- 

 municate with intracellular venous channels leading even into the 

 nucleus. To this view he still adheres, and it has been recently re- 

 affirmed by Holmgren and Studnicka. Moreover, the author believes 

 that the same holds good for other kinds of cell. 



Plasmosomes.! — Prof. J. Arnold brings forward further corrobora- 

 tions in support of his conclusion that the plasmosomes and their 

 modified products, the granula, cannot be regarded as unessential com- 

 ponent parts of the cell. He does not deny fibrils, indeed he has 

 himself described them ; but he protests against the position of Fleni- 

 ming and others, who maintain that the fibrillar structure is the only 

 important one. Experiments with intra vitam staining show that many 

 living cells contain granules, which may be imbedded in threads, or 

 may be linked together in thread-like structures; and it is maintained 

 that the larger stainable granula-like bodies arise from the cell-micro- 

 somes or plasmosomes. 



Moniliform Neurons in Invertebrates.} — Dr. J. Havet finds that 

 in earthworms, crayfishes, slugs, &c, the protoplasmic prolongations of 

 the nerve-cells show tag-like appendices resembling those found on the 

 prolongations of the neurons of vertebrates. The moniliform state of 

 the nervous prolongations also exists in invertebrates ; it has a more 

 conspicuous expression alter the animal has been subjected to the action 

 of chloroform, ether, morphine, strychnine, or chloral. 



* Aunt. Anzeig., xvii. (1900) pp. 44-8. t Op. cit., xvi. (1899) pp. 607-15. 

 t La Cellule, xvi. (1899) pp. 37-4G (2 pis.). 



