HISTORY OF THE FERTILIZATION PROBLEM 7 



(ova) in the females of toads, frogs, and salamanders, 

 prior to the act of fertilization, which according to the 

 epigenesists animates or creates the germ. For the 

 same reason the spermatists must also be wrong. Spal- 

 lanzani thus combated epigenesis as understood in the 

 eighteenth century, and also the ideas of the sperma- 

 tists, and he was led to deny that spermatozoa are neces- 

 sary for fertilization, and to hold that the fertilizing 

 power of the seminal fluid resides, not in the spermatozoa, 

 but in the fluid medium that accompanies them; and 

 this in spite of the fact that his final experiments really 

 proved the reverse. 



His work contains a great wealth of observation and 

 experiment, so that it will be possible merely to indicate 

 some of his chief results. In the first place he demon- 

 strated that in frogs and toads fertilization takes place 

 outside of the body, and for the first time he success- 

 fully carried out artificial insemination, thus laying the 

 foundation for the artificial propagation of many ani- 

 mals. In making these experiments he thought he found 

 cases in which seminal fluid devoid of spermatozoa would 

 fertilize and thus fell into the error, which he was so 

 ready to accept from his opposition to the spermatists, 

 that the fluid medium of the seminal fluid was the ferti- 

 lizing substance. He also investigated the conditions 

 of successful insemination, with reference to the duration 

 of fertilizing power, exposure to various chemicals, to 

 heat, etc. The amount of dilution of which the semi- 

 nal fluid was capable was likewise carefully investigated. 

 By experiment he excluded the idea that fertilization 

 might be an effect of an emanation, or vapor, arising 

 from the sperm, 



