ZOOLOGY FOR MEDICAL STUDENTS 



CHAP. 



j s f orrn k A) having at cac-h of its poles a minute, deeply-staining, 



centrosome. The two tetrads lie at the equator of the spindle 



ecomes split apart into two halves dyads which gradually 



FIG. 84. 



in . Isv.'/nx male <>n the left and female on tin- ri^lit (after Braner and 



i meiotie division the two tetrads are seen at the equator of the spindle 



a centt' nt at each pole of tlie spindle in the male but not in the female. B, The first 



ompl.-te, the two daughter cells each containing two dyad chromosomes 

 , the nial. hut very unequal in the female. C, Second meiotic division. In the male 

 ' IK resulting from the preceding division is dividing, the upper cell beintf shown 



at a later st.i^e than the lower. Kach cell contains two monads and a centrosome. In the female 



1 I .'. " and lecond polar body). I, first polar body; 

 II, second (in i; left hand fi trosome at each pole of the spindle has pre- 



.", in preparation for the second mitosis.) 



another towards tlu- poles of the spindle ; possibly owing 

 tn the rnmrartion ,| sjjindlc fibres attached to them (Fig. 84, B). As 



ijiart a ( onstriction appears round the equator of the 

 cell whirl) gradually deepens until the cell-body is completely divided 



