52 BIOLOGICAL LECTURES. 



stippling, and in the preparations it is stained blue.) Again, 

 you will find that the rays of the attraction sphere and the net- 

 work of the cone appear to be formed of a substance not con- 

 fined to these structures but forming the cytoplasm of the 

 entire egg. (In the preparations from which these figures 

 were drawn this substance stains red.) Again, the substance 

 which forms the centrosome or centrioles in Fig. 4 appears to 

 be only a part, an aggregation of a substance distributed 

 throughout the cytoplasm. By two different methods I have 

 been able to differentiate these microsomes from the rest of 

 the cytoplasm and archoplasm of the egg. 



Thus we have in this egg at least three cytoplasmic elements, 



cytoplasmic threads, archoplasm, and microsomes. This 



recalls Schloter's work on certain gland cells of Salamander, 



where he differentiates a like number of cytoplasmic elements. 



I have now shown what appears to me to suggest a like 

 origin an entirely cytoplasmic origin for the two struc- 

 tures (the fertilization cone and the sperm attraction sphere), 

 and in doing this I have shown the points of resemblance 

 between the two structures. Now let me show wherein it 

 appears to me they differ. 



In one case the anterior end of the head of the spermatozoon 

 seems to produce the effect upon the cytoplasm expressed by 

 the fertilization cone; and in the other case the middle-piece 

 seems to produce the effect upon the cytoplasm expressed by 

 the attraction sphere. We have a cone the moment any part 

 of the head penetrates the egg; if the head penetrates only a 

 short distance, we have only a small cone; when it penetrates 

 farther, we have a more pronounced cone. Thus only the 

 anterior end of the head of the sperm is necessary to produce 

 the fertilization cone; the cone can be formed before the middle- 

 piece enters the egg. On the contrary, the sperm attraction 

 sphere cannot appear until a relatively large part of the sper- 

 matozoon has penetrated the egg, until the middle-piece as well 

 as the head has entered into the cytoplasm. 



One cannot avoid seeking some explanation of the fact that 

 each end of the head of the spermatozoon produces a cyto- 

 plasmic phenomenon within the egg. If we recall those 



