JOURNAL OF ENTOMOLOGY AND ZOOLOGY 201 



fibers from nerve cells run as fibers, then divide into smaller masses 

 of fibrils, and at last break up Into numerous fibrils. The usual 

 demonstration of nerve cells with their branches as shown by the 

 Golgi or methylene blue methods, 1 believe, shows only the Idrger 

 and smaller branches from nerve cells, and the smallest branches 

 where the fibers break into fibrils are not shown at all. 



In this and other arthropods which I have studied, it seems to 

 me to be quite characteristic of the nervous system that many parts 

 show fine fibrilla" more clearly than they are seen in vertebrates. 

 This may in part be due to the nature of the insulating and support- 

 ive apparatus. As in Carcinus, described by Bethe, the optic tract 

 enters the mesal side of the globulus and splits up into smaller and 

 smaller parts, and is at last lost in the minute network of fibrils and 

 supporting substance. Large bundles from the outside may be 

 seen as dark masses here and there. These last are held in place 

 in the section by many connecting strands which join the fibers from 

 all sides. Some may be conducting fibrils, but it is hard to dis- 

 tinguish these from supportive. Probably most of the conducting 

 fibrils leave at or near the termination of the thicker part of the 

 fiber. The denser parts of the nervous system of this and other 

 arthropods, such, for instance, as the material of the globulus, are 

 composed for the most part of ultimate fibrillae whose relationships 

 at these points can only be conjectured at present because of their 

 minuteness, their great abundance, and because of the intermingling 

 of supportive or other materials of several little understood sorts. 

 An extensive comparativ^e study of these cienser masses with vari- 

 ous reagents should yield some interesting results. 



Tigroid substance, mostly in the form of dots and flakes, was 

 recognized, but not studied by special stains. The cells are sur- 

 rounded by a dense capsule of connective substance, and in some 

 cases the peripheral zone of the cell next the capsule is light. In 

 some, this light zone is speckled with dark dots or lines. Some of 

 these may be the ends of fibrilhc — in fact, some fibrils were traced 

 — others may be tigroid substance, or possibly the bodies recog 

 nized by Poluszynski in some Crustacea, although his are stained 

 bv other methods. 



