266 



WALTON. 



PLATE 2. 



Figure 8. Spermatid, showing fusion of the 'refringent vesicles.' 



Figure 9. Spermatid, showing advanced fusion of the 'refringent vesicles.' 



Figures 10 and 11. Early spermatozoa, showing the withdrawal of the 

 'refringent vesicles' to one end of the cell and their further 

 fusion, leaving the nucleus and surrounding plastochondria free 

 in the cytoplasm. 



Figure 12. Mature spermatozoon at time of copulation, showing refractive 

 body (cp. rfr.) formed by the fusion of the 'refringent vesicles.' 



Figure 13. Mature spermatozoon after remaining for some time in oviduct 

 of female, showing shrinkage in size of. the nutritive refractive 

 body (cp. rjr.). 



Figure 14. Mature spermatozoon, at time of insemination, which has 

 entirely used up refractive body. Plastochondria are scattered 

 all through the cytoplasm. 



Figure 15. Fertihzed egg with pronuclei not as yet united, showing persist- 

 ence of male plastochondria. 



Figure 16. Fertihzed egg with pronuclei uniting, showing last remnants of 

 male plastochondria, the most of which are scattered through- 

 out the cell. 



