Fig- 25. 



A spermatocyte preparing for the first or meiotic division; a large 

 karyosome is present and the rest of the chromatin is scattered in the 

 form of granules on the achromatic network of the nucleus ; on the top 

 of the nucleus is the centrosphere with two centrosomes. , spireme 

 with a single row of chromatin granules ; the loops of the spireme show 

 a distinct polarity. C, early stage of synapsis, the chromatin granules 

 and the spireme ribbon are divided longitudinally. D, twelve bivalent 

 chromosomes of various shape becoming arranged round the equator of 

 the spindle. E, metaphase of the meiotic division ; each bivalent 

 chromosome is being divided into its two components, one of which is 

 being drawn to each pole of the spindle. F, nuclear telophase and first 

 division of the spermatocyte. G, two secondary spermatocytes prepar- 

 ing for division ; the upper figure showing an earlier stage of mitosis 

 than the lower ; the nucleus of each spermatocyte contains twelve 

 unh'alent longitudinally-split chromosomes. //, the upper spermatocyte 

 shows the metaphase, the lower the early anaphase of the first post- 

 meiotic (homoeotype) division. _/, the two secondary spermatocytes have 

 divided to form four spermatids ; the nuclei are shown in different stages 

 passing from the late anaphase to the resting condition. Note that the 

 figures G, //, / are drawn on a somewhat smaller scale than the rest. 



