SPERMATOGENESIS OF CANCER MAGISTER. 2 95 



Among the Crustacea, parasynapsis has been established in 

 some of the Copepoda (Lerat, '05; Matschek, '09; McClendon, 

 '10; and Kornhouser, '15), and also in one of the Decapoda 

 (Fasten, '14). In the decapod crustacean Cambarus virilis, 

 I ('14) showed that during the growth period, the chromosomes 

 conjugate in parasynaptic fashion, and as already pointed out 

 elsewhere in this paper, this is the type of conjugation which 

 occurs in Cancer magister. In both Cancer magister and Cam- 

 baras virilis, the great difficulty encountered in the study of 

 synapsis was the immense number of chromosomes. However, 

 after prolonged and careful study of the various stages in the 

 growth period of these animals, one finds it rather difficult to 

 interpret the conjugation of the chromosomes in any other way 

 than by parasynapsis. 



B. The Chromatoid Bodies. 



Ever since Wilson ('13) called attention to a chromatoid body 

 in the spermatogenesis of Pentatoma, similar structures have 

 been described during the spermatogenesis stages of other forms. 

 In Cambarus virilis (Fasten, '14), two such bodies were found 

 which could be traced into the spermatid stages and then all 

 traces of them were lost. In Cancer magister, a pair of chroma- 

 toid bodies make their appearance during the synizesis stage of 

 the growth period, and during the reduction division these pass 

 to opposite poles, so that the secondary spermatocytes each 

 possess a chromatoid body. During the equation division, this 

 body passes undivided to one pole, resulting in two types of 

 spermatids, one type possessing a chromatoid body, while the 

 other type is minus such a structure. It is also of interest that 

 the chromatoid body is eventually expelled from the first type 

 of spermatid thus playing no further part in spermatogenesis. 



Concerning the nature and function of the chromatoid body, 

 very little can be said. In only two forms, namely Pentatoma, 

 (Wilson, '13) and in the decapod under consideration Cancer 

 magister, has the full history of this structure been traced, and 

 in both cases, it is expelled from the spermatids, thus appearing 

 to play no definite role in the mature spermatozoa. Wilson 

 ('13), in discussing the chromatoid body, makes the following 



