kStudics in Crustacean Sporniatogenesis. 4{>r) 



with the egg, thus orienting the spermatozoon. The processes then 

 contract until the nucleus touches the circumference of the egg. 

 The attachment of the processes is possibly by the excretion of some 

 adhesive substance, but also mechanical ; the egg membrane is finely 

 porous, and into the pores portions of the processes insert them- 

 selves. Koltzoff believes that the explosion of the capsule then forces 

 the nucleus and the proximal centrosome into the egg, the derivatives 

 of the distal centrosome and the processes being cast off. These 

 observations lend additional weight to the homology outlined above ; 

 the capsule fulfills the function of a tail, namely, that of conveying 

 the nucleus and centrosome into the egg. 



Development of the Spermatzoon from the Sper:matid. 



Koltzoff has described with much interesting detail the develop- 

 ment of the Decapod spermatid. He traces the origin of the middle- 

 piece and tail from the mitochondrial granules and follows the 

 peculiar development of the distal centrosome within the inner tube 

 of the capsule. 



Hippa is the only Decapod from which I obtained a complete 

 series of stages illustrating the transformation of the spermatid. 

 The fixing fluid employed, namely Flemming's strong solution, does 

 not bring out well either the mitochondrial granules or the distal 

 centrosome. According to Benda (1903), the proportion of acetic 

 acid in this fluid is great enough to cause swelling and disappear- 

 ance of the mitochondrial granules. It is probable, however, that 

 in an animal so nearly related to those described by Koltzoff their 

 development would be much the same. Of the forms described by 

 Koltzoff, that most nearly related to Hippa is Pagurus striatus. 

 Compared Avith this, the spermatozoon of Hippa is more contracted ; 

 both the head and capsule are broader and shorter and the demarca- 

 tion between head and middle-piece is less shai-p. In these respects 

 it approaches more nearly to the S. contracta of the Brachyura. The 

 inner tube of the capsule is closed at its distal extremity by a plug. 

 In my preparations of Hippa the tube is much narrower than in 

 Koltzoff's figure of Pagurus and in the immediate vicinity of the 

 plug the wall of the capsule is somewhat thickened. (PI. 3, 

 Hi, 34.) 



