588 NATHAN FASTEN 



most of his time. The other species, probably Cambarus im- 

 munis, was used for com.parison, the shdes having been prepared 

 by Mr. Powers of Lincoln, Nebraska. 



The testes of Cambarus virilis were fixed in various fluids, such 

 as: (1) Bouin's fluid; (2) Carnoy's fluid; (3) Carnoy's and 

 Lebrun's fluid; (4) Five per cent corrosive-acetic mixture; 

 (5) Flemming's strong fluid; (6) Gilson's fluid; (7) Hermann's 

 fluid; (8) Meves-Duesberg modified Flemming fixative; and 

 (9) Zenker's fluid. 



The best results were obtained with fluids (7) and (8). Zenk- 

 er's fluid also gave fairly good results for fixing the gross structure 

 of the cell, but it was not valuable for the study of details. The 

 Hermann and Meves-Duesberg fluids were the most valuable 

 for the structural study of the nucleus and the cytoplasm. The 

 chromatoid bodies in the cytoplasm were best fixed by these 

 reagents. Both these fluids, especially that of Meves-Duesberg, 

 altered the cell configuration but slightly. The Hermann 

 fixative was particularly valuable for the study of synapsis and 

 for making chromosome counts. 



Sections were cut from 4 to 7ju in thickness and stained in either 

 of the following ways : 



(1) Delafield's hematoxylin and eosin; (2) Heidenhain's iron- 

 hematoxylin and acid fuchsin or Orange G; (3) Safranin with 

 gentian violet, lichtgriin, or lichtblau; and (4) Sulfoalizarin- 

 sauren natron and krystalviolet. 



The Meves-Duesberg method gave the most beautiful results, 

 and was perhaps the method of greatest importance for the study 

 of the chromatoid bodies and the cytoplasmic granules (mito- 

 chondrial granules?). The essential steps in this method are as 

 follows : 



1. Material is fixed for twenty-four hours in a mixture con- 

 taining, (a) 15 cc. of 1 per cent chromic acid, (b) 4 cc. of 2 per 

 cent osmic acid, and (c) 3 drops of glacial acetic acid. 



2. Wash for one hour in water and then for twenty-four hours 

 in a mixture containing 100 cc. pyroligneous acid and 1 gram 

 chromic acid. 



