PHOTOGRAPHS OF THE EGG OF ALLOLO- 

 BOPHORA FOETIDA. 



KATHARINE FOOT and ELLA CHURCH STROBELL. 



I. 



This paper is the first of a series in which we hope to 

 make a careful comparative study — illustrated with photo- 

 graphs — of the effects of various fixatives on the cytoplasm 

 of the egg of Allolobophora foetida.^ 



In addition a number of preparations have been photographed 

 to illustrate the following points : 



The morphological resemblance of the fertilization cone to 

 the male aster. 



The position of the middle-piece in the male aster. 



The origin of the sperm granules. 



The early stages of the development of the pronuclei. 



The presence of osmophile granules in the nucleoli of the 

 germinal vesicles. 



The photographs have been taken at only two magnifications 

 (660 and 950). No photographic feats have been attempted, 

 photography being used merely to register the points we wish 

 to illustrate, and the higher magnification has not been used 

 where our aim could be achieved by the lower. 



Cytoplasmic Reaction to Fixatives. 



Our aim is to make a comparative study of the effect pro- 

 duced not only by the compound fixatives, but by the compo- 

 nent parts of each. If with a given fixative we find a definite 

 cytoplasmic configuration, can this be materially changed by 

 omitting; one of the constituents of the fixative } If this 



1 A few photographic illustrations of this comparative work were published in 



1898. Foot and Strobell, " Further Notes on the Egg of Allolobophora foetida," 



Zoological Bulletin, vol. ii, No. 3. 



601 



