THE NERVOUS CYTOLOGY OF PERIPLANETA ORIENTALIS. 345 



VI. CELLS FIXED IN ABSOLUTE ALCOHOL. 



i. Technique. — Fresh ganglia were immersed in absolute alcohol for several 

 hours, embedded, cut, and stained as above described for picroformalin preparations. 



2. Observations. — The walls of the cells-spaces were much more shrunken and 

 distorted than by any previous method. The nuclear membrane was regularly burst 

 outward, and often its remnants could not be identified. The clear area (Figs. 17, 18)> 

 representing the previous site J of the nucleus, was thus somewhat larger than 

 the nucleus itself had been. It was sometimes quite empty and sometimes con- 

 tained some irregular amorphous masses. The granular area of the cell-body was rep- 

 resented by a rather narrow perinuclear ring of granules, rarely showing any tendency 

 to areolar or reticular disposition, but usually denser on one side of the nucleus than 

 on the other, and occasionally exhibiting irregular condensations even near the 

 periphery. The outer zone of the cell-body was replaced, for the most part, by 

 empty spaces containing a few shredded remnants of reticulum, most frequently seen 

 at the transition between the outer and inner zones (Figs. 17-19). 



VII. CELLS FIXED IN VAN GEHUCHTEN'S FLUID. 



i. Technique. — Fresh ganglia were immersed in Van Gehuchten's fluid * for one 

 minute, then in 95% alcohol. The subsequent treatment was as already described. 



2. Observations. — The appearances, though somewhat more favorable than 

 those obtained with picroformalin, were so similar as to need no separate description. 



VIII. THE FRESH CELLS. 



The various appearances occurring after the different methods of fixation, all 

 suggestive of some degree of damage to the cell structure, indicated the necessity of 

 some standard for comparison, and this could only be satisfactorily obtained by study- 

 ing the cells as they appeared during life. 



i. Technique. — A fresh ganglion, dissected out as rapidly as possible, was teased 

 apart on a slide, flooded with equal parts of Nissl's methylen blue and a 0.5% solu- 

 tion of sodium chloride, and examined at once. A number of ganglia were subse- 

 quently handled in the same way, the only modification being the substitution in 



* Van Gehuchten's fluid: Absolute alcohol, 300 pts.; chloroform, 150 pts.; glacial acetic acid, 50 pts. 



