THE SPEEMATOZOA OF ALLOLOBOPHOEA FOETIDA. 



KATHARINE FOOT AND ELLA CHURCH STROBELL, 

 WoocVs JToll, Ifans. 



With 1 Plate. 



In the siDermatozoun of Allolohophora we have demonstrated three 

 centrosome-like structnres, one at the base of the spine, one at the an- 

 terior, and one at the posterior end of the middle-piece. Heretofore we 

 have differentiated these structnres at such rare intervals, we could not 

 claim for them any morphological value, but quite recently, by the aid 

 of photography, we have been able to demonstrate these bodies with 

 sufficient constancy to warrant a consideration of their morphological 

 and functional significance. Do these bodies represent merely points 

 of insertion for the spine, middle-piece and tail, comparable to the basal 

 bodies of cilia, or have they a bearing upon the problems of fertilization ? 



The morphological value of the apical centrosome-like body is en- 

 hanced by the fact that a few investigators, Platner (12), Carl Messing 

 (11), and Field (3), have traced the ceutrosome of the spermatocytes to 

 the apex of the head of the spermatozoon, and in one case at least, this 

 apical centrosome appears to function in the fertilized egg, as the ceutro- 

 some of the male attraction-sphere. To this may be added the interest- 

 ing observations of King (7), Avho has shown in the egg of Bufo that a 

 male aster is formed at the apex of the head of the spermatozoon. 



The morphological value of the centrosome-like body in the middle- 

 piece is enhanced by the interpretations of a large number of investiga- 

 tors who have traced the centrosome of the spermatocytes to the middle- 

 piece of the spermatozoon, in many cases this centrosome being iden- 

 tified in the egg, as the centrosome of the male attraction-sphere. 



In the middle piece of Allolohophora, however, we have demonstrated 

 two ceutrosome-like bodies instead of one, and in this connection Len- 

 hossek's (8), observations on the spermatogenesis of certain vertebrates 

 are of interest. He identifies two centrosomes in the middle-piece, 

 these having originated by the division of the centrosome of the sperma- 

 tid. He shows also a centrosome-like body at the apex of the head — his 

 Alrosoma — which he claims, however, has no connection with the centro- 



