384 



CHARLES H. SWIFT 



content, and the preservation of the mitochondrial granules and 

 attractions sphere was a decided asset. 



In this work only the testes were fixed and not the whole 

 embryo, as was the custom, when dealing with the younger 

 stages. 



In the case of the youngest stages used in this investigation, 

 the testes were allowed to remain in the killing fluid 24 hours 

 but as there were signs of over-fixation in the sections, this time 

 was reduced to 10 hours with much better results. 



All the sections were cut 4/z in thickness, and following the 

 acetic-osmic-bichromate fluid stained by Bensley's anilin-acid 

 fuchsin — Wright's blood stain method and the anilin-acid-fuch- 

 sin-methyl green method. There is no need of entering into 

 detail in regard to these staining methods since they have been 

 described by Bensley ('11), Cowdry ('12), and Swift ('15). 



Following Meves' fluid the iron hematoxylin stain was 

 employed. 



The following table will show at a glance the number of stages 

 employed, their age, and the methods used in fixation and 

 staining. 



