No. 3] THE EGG OF ALLOLOBOPHORA FOETID A. 131 



shows a definite structure of the cytoplasm and an aj^proxi- 

 mately definite distribution of the granules ; osmic acid was 

 then used, not as a fixative, but as a stain which might select 

 the deutoplasmic granules alone. After a few minutes in 1% 

 osmic, the eggs were hardened, imbedded, sectioned, and mounted 

 in glycerine without further staining. An examination of the 

 sections showed the granules intensely blackened, and as they 

 were apparently the only constit- 

 uents in the cell that responded 

 to the osmic, we have designated 

 them osmophile granules (Photo. 

 12 and Text-fig. I). The nu- 

 cleoli in the pronuclei, and when 

 present throughout the cyto- 

 plasm, were not blackened by 

 the osmic, and the centrosomes, 

 which were occasionally visible 

 in the unstained sections, were fig. i.- section of^^^^^^I^order, showing 

 a brownish-yellow. With the °"^ ^""""^ °^ distribution of the osmopwie 



^ granules. Osmophile granules in cytoplasm 



diaphragm open, the intensely and sphere drawn with camera lucida. Rays 



1 1 1 1 .1 1 aiagrammatic. 



black osmophile granules are 



most sharply differentiated from the centrosomes and the green- 

 ish refractive nucleoli. Photographs were taken of many of 

 these sections, and numerous camera sketches were made, and 

 a comparison of these with the sketches previously made of the 

 granules that had been differentiated with methyl green (6) 

 showed beyond question the identity of many of the latter with 

 the osmophile granules. The above-mentioned unstained sec- 

 tions were then soaked in warm xylol twenty-four hours and 

 left mounted in xylol balsam until the osmophile granules had 

 so nearly disappeared (at first the xylol merely removes the 

 blackening caused by the osmic) that their presence could be 

 detected only by comparing the sections with photographs 

 which indicated exactly where to look for each granule. The 

 sections were then stained with orange-methyl green, and the 

 faded osmophile granules selected the green and became again 

 distinctly visible. Other sections were stained with acid 

 fuchsin before being mounted in glycerine, and these showed 



