126 



J. Thomas Patterson. 



r innini i' 'iii M" ii'i , ii i ii' ii :i r 



cm 



Ytg. 6.— a nest of four supernumerary sperm nuclei. X about 600. 



Fig. 7.— a sperm head lodged in the vitelline membrane. The sperm had 

 evidently been stopped in the act of entering the egg. X about 600. 



Fig:* 8.— Three sperm heads embedded in the chalazipherous layer of albumin 

 and located next to the vitelline membrane. Both of these figures (7 and 8) 

 are taken from the central region of the egg shown in Fig. 10. X about 600. 



Pig. 9._A diagram of the blastodisc shown in Fig. 1, showing the dis- 

 tribution of the supernumerary sperm nuclei. The black dot indicates that 

 the nucleus is located more or less superficially in the disc; while a dot 

 marked prime one shows the location of a nucleus that is situated deep in the 

 disc, and one marked prime two. a nucleus that is undergoing fragmentation. 

 The broken line, A— B, is the plane of the section shown in Fig. 2. X 18. 



Fig. 10.— Diagram of a blastodisc of an egg taken from the oviduct three 

 hours after fertilization, shortly after it had entered the isthmus. This shows 

 six supernumerary sperm nuclei. Line A— B is the plane of the section shown 

 in Fig. 11. X 18. 



