244 KIY03HI JIASUI. 



usually clisippears diuiun; the second division. Moreover, it is olivioiis thit 

 when the cell is divided into tw(j it enters into oue of the daughter cells 

 without divisiou, which produces two kiuds of tha spermatids iu the mouse, the 

 oue with and the other without the chi-omatoid body. 



From these it seems more probable that the chi-omatoid boly is uot an 

 essential organ for the develojimeut of sperm-itozoa. Although it3 origm can 

 uot be determined with any certainty, fi'om the jiieriod of its appearance and 

 its staining reaction it seems more probable that the chromatoid body is not a 

 proper c;>'toplasmic sfcnictnro but originatss fi'om the nucleus. It? chemical 

 iiatra'e seems to be different fi-om that of the chi'omatin gi'auules but is similar 

 to that of the nucleoli which appear at the gi'owth period of the sj^ermatocyte. 



Summary. 



I. Obsebvation in the Mouse. 



1. Tlie resting nuclei of the spermatogouial cells usually contain one 

 large nucleolus and several chromatin masses. 



2. The number of siaermatogouial cln-omosomes may ba coimtad as forty. 

 According to size and form, these are found to be in pah's. Every chromo- 

 some simultaneously begins to divide at one end where the spindle fiber 

 attaches ; no special chromosomes with different behavior arc to be seen among 

 them. 



3. In the yoimg spermatocyte a slight polar aggregation of the chromatin 

 threads usually appears, which cou'esioonds to the synizesis of other animals. 



4. In the post-synaptic stage when tha nucleolus appeaiä the clu-omatiu 

 Spiremes are stained with both methyl-gi'ean and acid-fuchsin at the same time 

 ^vith Auerbach's method. Together with the gi-oM-th of the cells and of the 

 nucleoli, this change of staining capacity increases, attaining the maximum in 

 the propliase stage in which tha ring shaped chromosomes begin to appear. At 

 the late prophase the chromosomas are again stained with methyl-green only. 

 In this stage the nucleolus, except in soma few cases, entirely disap^jears. 



5. In the prophase several kinds of the ring shai^ed chromosomes appear 

 wliich are condensed to the bivalent clu"omo3omcs iu the meta,phasc of the first 

 division. Tlie number of the bivalent cliromosomes may 1x3 counted as twenty. 



