224 KIYOSBU MASOI. 



difficult to determine this with any certainty since their size is loo small to 

 measure. In the second reduction division the mitochondria repeat the same 

 behavior aT in the first (Fig. 63). 



The chromatoid body: — During the fii-st division the chromatoid body 

 usually hes near the pole of the spindle (Fig. 43). At the telojohase it 

 remains without division and enters into one of the daughter cells. Some- 

 times beside the chromatoid body a large roimd body apj^eai-s which is 

 stained deeply with acid-fuchsin like the chromatoid body (Fig. 45). In the 

 succeeding stage this body can not be distinguished from the chromatoid 

 body. Judging fi-om the behavior and situation this Ijody is probably the 

 remnant of the nucleolus which appears in the early raetapliase, but it is 

 uncertain whether it remains till the transformation of the spermatid as the 

 true chi-omatoid body, or disappears in the teloi^hase of the fii-st division. In 

 the second spermatocyte the chi'omatoid body is very conspicuous and is 

 probably the same as that seen in the telophase of the first division. In the 

 second reduction division the chromatoid body re^^eats the same behavior as 

 in the first, but in the telophase it lies near the cell plate (Figs. 62-64, 66, 

 141). WTien the cell is divided into two the chromatoid liody enters into 

 one of the daughter cells (Fig. 142). Sometimes some extra small botlies 

 appear which are probably produced by division of the chromatoid body. 



It is remarkable that in the second spermatocyte the chromatoid body 

 becomes more conspicuous and is deeply stained with acid-fuchsin (Figs. 141, 

 142). 



The resting stage of the sccuudiry spermatocyte : — As in other mammals 

 the resting stage of the secondary spermatocyte is found in the mouse. The 

 nuclei of the resting secondary spermatocjies contain several chromatin 

 masses and no special chromosome nucleoli can be found. The ichozome, the 

 chromatoid body and the mitochondrial granules appear in this stage, the 

 latter being scattered throughout the cytoplaim. 



33. The reduction division in the rabl>it. 



The first reduction division :— In tho motaphase of the fii'st reduction 

 division the chi-omosomes have a tendency to mass togxither so closely that 

 it is (Ufficult to make out their individualities distinctly (Fig. 108). That thsi 



