Davis.^- Spermatogenesis. 



PLATE 8. 



All figures are of Steiroxys trilineata. 



Fig. 189. Polar view, metaphase of first maturation tlivision. The rod- 

 shaped chromosome is the monosome. 



Fig. 190. Anaphase of first division. The monosome can be seen near the 

 right pole. 



Fig. 191. Early telophase of first division. The longitudinally split mono- 

 some has lagged behind the autosomes. 



Fig. 192. Late telophase of first division. 



Fig. 193. Semiresting stage of secondary spermatocytes. In one cell the 

 monosome lies within, in the other without the nucleus. 



Fig. 194. Prophase of second division. The inonosome is seen below. 



Fig. 195. Metaphase of second division. 



Fig. 196. Early anaphase of second division in n cell which lacks the mono- 

 some. 



Fig. 197. Later anaphase. The monosome is just dividing. 



Fig. 198. Late telophase of second division. The monosome is not present. 



Fig. 199. Late telophase of second division. The monosome is seen pro- 

 jecting from each mass of daughter chromosomes. 



Fig. 200. Early spermatid. The monosome is still compact. 



Fig. 201. Later spermatid. The monosome is lacking. 



Fig. 202. Same stage as Figure 201, but the monosome is present. 



Fig. 203. Same stage as Figure 201. 



Figs. 204^212. Successive stages in the metamorphosis of the spermatid. 



