198 BIOLOGY: GENERAL AND MEDICAL 



experimentally treated a variety of unfertilized eggs in 

 such manner as to bring about artificial parthenogene- 

 sis. In natural sexual fertilization the spermatozoon 

 accomplishes the double purpose of furnishing the neces- 

 sary stimulus at the same time that it effects amphimixis, 

 and thus affords opportunity for the variation of the 

 species. 



REFERENCES. 

 Same as for Chapter VII. 



