356 THE NERVOUS CYTOLOGY OF PERIPLANETA ORIENTALIS. 



various circumstances. This deposit is caused by every fixing reagent used in the 

 foregoing work, by post-mortem changes (possibly from the acid reaction that they 

 induce), and during life by acute arsenic poisoning. It, or rather the material from 

 which it is derived, is reduced by prolonged nervous activity, as indicated by the strych- 

 nine experiments and demonstrated by the results of Faradization, which seems to 

 indicate that it in some way represents the potential energy of the cell. It is soluble 

 in a 0.4% solution of sodium hydrate. In electing the strands of the reticulum as 

 its location when precipitated it follows the usual law in such matters. It seems to 

 correspond with the chromophilic substance of the nerve-cells in higher vertebrates. 

 Its occurrence during life under the influence of arsenic suggests one of the ways in 

 which this drug may affect nervous tissues, for such a change in the protoplasm would 

 necessarily affect and possibly entirely arrest its functions. Whether the reticulum 

 indicates an actual network anastomosing in space or an emulsiform structure I do 

 not know, but the appearance of the fibrillary zone after picroformalin, etc., the 

 appearance of the fresh cells, and especially the acute-angled anastomosis in the nerve- 

 fibre, all point to a true reticulum. 



No classification of the cells could be arrived at, as their relative sizes, the 

 appearance of their network, and the amounts of chromophilic deposit all showed 

 all gradations between the extreme limits of variation in each instance. 



The nerve-fibres show essentially the same reticular structure as the cell-body. 

 No chromophilic deposit was observed in them. 



In closing I wish to acknowledge my indebtedness to Dr. Ira Van Gieson, who 

 originally suggested the work and afforded the facilities for its execution, besides 

 giving most helpful advice at many critical points. 



XX. BIBLIOGRAPHY. 



Bethe, A. 



'96. Eine neue Methode der Methylenblaufixation. Anat. Anz., Bd. 12, No. 18, pp. 438-446. 

 Held, H. 



'97. Beitrage zur Struetur der Nervenzellen und ihrer Fortsatze. Zweite Abhandlung. Arch. f. Anat. 

 Physiol., Jahrg. 1897, Anat. Abt., pp. 204-294, Taf. 9-12. 



Parker, G. H., and Floyd, R. 



'95. The Preservation of Mammalian Brains by Means of Formol and Alcohol. Anat. Anz., Bd. 11, No. 5, 

 pp. 156-158. 



