333 The Spermatozoa of Allolobophora Foetida 



some of the spermatid, arising merely as a thickening of tlie sphere sub- 

 stance. With improved technical methods we hope to be able to identify 

 within the egg the three centrosome-like bodies of the spermatozoon of 

 Allolohophora and determine whether any of them function as focal 

 points for astral rays. For the present the only evidence in the egg, 

 indicating that we may expect to find a centrosome in the spine and in 

 the middle-piece is that the cytoplasm of the egg reacts to hotli spine and 

 middle-piece, this reaction being expressed by two morphologically sim- 

 ilar structures, the fertilization cone and the sperm aster, these two 

 structures in turn resembling morphologically the asters of the matur- 

 ation spindles, each of which contains a centrosome. 



On several occasions Ave have called attention to the similarity of the 

 fertilization cone and the male aster, further homologizing these struc- 

 tures to the poles of a spindle. ^Ye quote the following from a former 

 paper : " It is impossible to avoid drawing conclusions as to the mor- 

 phological significance of the resemblance between the male aster and 

 transverse sections through the fertilization cone. The rays and the 

 central aggregation of Archoplasm are as pronounced in the one as in 

 the other, suggesting that each end of the head of the sperm — the spine 

 and the middle-piece — produces on the cytoplasm of the egg a like mor- 

 phological effect. This would indicate that the spine and the middle- 

 piece are of the same substance, though the identity can not be com- 

 plete, as the cytoplasm does not react to the two structures at the same 

 stage of the development of the egg. . . . The effect produced by the 

 spine is made, however, by a moving object (the sperm entering the egg) 

 and we have thus a different shaped aster — a cone shaped aster. Is it 

 possible that this may have any bearing on the opposing interpretations 

 of various authors, some asserting that the anterior end of the head of 

 the sperm produces the male aster, and others, that the posterior end 

 of the head (the middle-piece) produces it ? 



" If we accept the interpretation of those authors who claim to have 

 traced a part of the aster of the spermatid, to both spine and middle- 

 piece, may we not regard that part of the spermatozoon (including spine, 

 head and middle-piece) as an attenuated spindle, and expect that each 

 end of this spindle will produce a like morphological effect upon the 

 cytoplasm of the egg? " (5) page 605-G. 



When the above was written we had not succeeded in establishing the 

 identity of centrosome-like bodies in either spine or middle-piece, 

 though homologizing the spine, head, and middle-piece of the spermato- 

 zoon to an attenuated spindle, made this identification very desirable. 



If it can be proved that the fertilization cone and male aster are mor- 



