262 PHOTOMICROGRAPHY 



44, Figs. A and B). The root apex of Fritillaria was 

 fixed in Hermann's fluid. The developing egg of Ascaris 

 in acetic alcohol. These two reagents are valuable for 

 cytological work, particularly for karyokinesis. 



Both were stained in Heidenhain's iron hsematoxylin 

 according to the procedure given on page 265. This 

 stains the chromatin sharply. The cytoplasm was 

 counterstained in eosin (Fig. A), or in orange G. (Fig. B). 



Sections of Mouse (Plates 15 and 30). Fixed in 

 Perenyi's fluid. Stained in bulk in borax carmine (p. 264), 

 the sections counterstained in aniline blue. The colours 

 intensified and further differential staining obtained by 

 washing in picric acid, dissolved in alcohol or in the 

 clearing xylene. 



