FERTILIZATION ON PARTHENOGENESIS. 159 



the Hertwigs ('87). Sperm enter these eggs over-exposed to 

 butyric acid, in large numbers and evidently at any point on the 

 circumference. Eggs exposed to butyric acid for 2^ minutes 

 were inseminated, preserved and sectioned. Fifteen minutes 

 after insemination the eggs contained one or many sperm lying 

 in the cytoplasm either unchanged or in various stages of ac- 

 tivity. Many possessed asters and some even though quite 

 widely removed from the egg nucleus, appear very much like 

 the swollen sperm in normal fertilization just before copulation 

 of the nuclei. Many sperm were undergoing fragmentation with 

 no indication of an aster. 



Forty-five minutes after insemination many eggs had formed 

 amphiasters appearing quite normal. Polyspermy however 

 seemed predominant: many figures were composed of three, four, 

 or five spindles variously linked together; different sets of amphi- 

 asters within the same egg but completely isolated from each 

 other are often to be noted. Large numbers of sperm may be 

 found bunched together in a mass, the whole being surrounded 

 by protoplasmic radiations that extend only a short way through 

 the cytoplasm. Such sperm masses usually give evidence of 

 quite an extensive amount of disintegration. Many of the eggs 

 with definitely formed chromosomes dispersed along the rays of 

 a monaster show sperm lying inactive. Many eggs also are 

 present in which neither egg nor sperm seem to undergo any 

 change, at least, within the space of two hours. 



In a series of this kind we see all gradations of completeness 

 of the process of fertilization from total absence of any reaction 

 to processes very greatly resembling the normal behavior of the 

 two elements. Some of the eggs have evidently suffered more 

 from the activating influence of butyric acid than others and are 

 consequently less responsive to the normal stimulus exerted by a 

 spermatozoon. 



C. Prolonged Exposure to Butyric Acid. The last point in 

 the fertilization curve to be considered is the point at which 

 fertilization absolutely ceases. From the highest point in the 

 curve after an over-exposure to butyric acid, a gradually declining 

 amount of fertilization is possible until no indications of a 

 reaction are at all visible. This is from five to fifteen minutes' 



