344 THE NERVOUS CYTOLOGY OF PERIPLANETA ORIENTALIS. 



delicate in appearance than after osmic fixation. It always entirely enveloped the 

 granular zone. The main strands were disposed, for the most part, in a centripetal 

 direction, though the fibrillse from the point of origin of the nerve-fibre sometimes 

 passed some distance down one border of the cell (Fig. 11). There was less of a ten- 

 dency for the individual fibrillar, which were very fine and clear of granules, to collect 

 into bundles. The network varied markedly in the size of its spaces, often giving 

 the appearance of being under centripetal tension, and it gave evidence of different 

 degrees of damage. The nodal points were but very slightly enlarged. As this 

 reticulum passed over into the inner zone, the granules and masses which appeared 

 first at the nodal points and then along its strands finally obscured it more or less 

 completely (PL XXVI, Fig. 14). 



IV. CELLS FIXED IN CORROSIVE SUBLIMATE. 



i. Technique. — Fresh ganglia were immersed in Lang's solution* for 45 minutes. 

 The subsequent treatment was identical with that used after picroformalin, with the 

 exception that iodine was added to the alcohols to remove all traces of mercury. 



2. Observations. — The appearances were practically identical with those pre- 

 sented after picroformalin, with the exceptions that the walls of the cell-spaces were 

 more shrunken and the reticulum of the outer zone of the cell-body much more evidently 

 lacerated and distorted (PI. XXVI, Fig. 15). 



V. CELLS FIXED IN CHROM-OXALIC. 



i. Technique. — Fresh ganglia were immersed in chrom-oxalic t fluid for 10 

 minutes. The subsequent treatment was identical with that for picroformalin prep- 

 arations. 



2. Observations. — The cells showed a degree of damage to the reticulum interme- 

 diate between that produced by picroformalin and corrosive sublimate, and besides 

 this they took the stain reluctantly. There was also more tendency to matting of 

 the fibrils of the outer zone. Otherwise the appearances were in no way different 

 from those already described for picroformalin (Fig. 16). 



* Lang's solution: Sodium chloride, 120 pts.; mercuric chloride, 60 pts.; glacial acetic acid, 120 pts.; dis- 

 tilled water, 2000 pts. 



t Chrom-oxalic fluid: 1% aq. sol. chromic acid, 30 pts.; 95% alcohol, 30 pts.; 10% aq. sol. oxalic acid, 

 40 pts. 



