228 KIYOSHI MASCI. 



to pi'oceed from tlie posterior one backward towards the surface of the cell 

 (Figs. 69-71). 



The idiozome : — Later on tLe granules of tlie idiozome gradually gi-ow 

 and these collect together and form a large mass which usually lies close t^ 

 the wall of the idiozome, being smroimded by a clear space (Figs. 67-69). 

 "When the two centrosomes appear this mass is found to lie in close contact 

 to the anterior part of the nuclear wall where a slight depression appears, 

 while the remnant of the idiozome in which ^acuole can be seen, gradually 

 diminishes in size, becoming more and more homogeneous (Figs. 69-81). 



The mitochondria : — A small number of the mitochondrial gi'anules still 

 remains in the cell body, the main portion of them being gathered at the 

 posterior part of it (Fig. 69). 



The chromatoid body ; — The chromatoid body remains without any 

 change and usually lies near the centrosome, appearing as a spheric body 

 (Fig. 70). 



Period n. 



The nucleus: — At the beginning of this period the nucleus begins to 

 elongate and fiually assumes a pear-shajje (Fig. 72). Some of the chromatin 

 granules begin to collect on the inner surface of the nucleus, while several 

 masses are left behind, £ind are so faintly stained with iron-haematosylin, that 

 the nucleus appears more or less homogeneous (Figs. 72-74). 



The centrosome : — The anterior centrosome which is situated on the 

 nuclear wall, gi-adually grows and flattens, while the axial filament elongates 

 more and more until it proceeds backwards and projects out of the cell body 

 (Figs. 72-74). 



The acrosome : — The acrosome which is formed by the condensation of 

 the granules of the idiozome now grows and flattens, to spread out finally on 

 the aaiterior surface of the nuclear wall, while the remnant of the idiozoa:e 

 gi'adually diminishes in size (Figs. 72-74). 



" Schwanzmanschette " :— At the end of this stage the " Schwanz- 

 manschette " appears at the posterior part of the nuclear wall (Fig. 72). Its 

 fcjrm is entirely similar to that of the guinea-pig, as described by Meves 

 ('99), but the filamentous structure as indicated by him can not be seen. 



