206 MR. NEWPORT ON THE IMPREGNATION OF 



questions to the test in one set of experiments. But, in attempting to do so, it was a 

 matter of importance, first, to obtain some approximative knowledge of the actual 

 quantity of spermatic fluid employed by SPALLANZANI, in his more remarkable expe- 

 riments, to enable me to compare the results of my observations with those of his. 

 SPALLANZANI states, that by his mode of obtaining the seminal fluid, by vivisection, he 

 could only procure from "two to three grains*" from each individual. Three grains 

 weight of fluid are equal, by measure, to nearly three minims of our medicinal standard. 

 But it may be presumed that in so delicate an operation as that of removing the fluid 

 from the vesiculse seminales, from which SPALLANZANI states he usually obtained it, 

 he could rarely be very precise in his determination of the quantity. I assume, there- 

 fore, for the sake of comparison, that the quantity he speaks of as "a grain" was 

 about equal to a minim of our medicinal measure. Three grains of fluid (? minims), 

 he says, were mixed with a pint and a half of water, and one drop of this mixture 

 (the seminal fluid in which was equal to 3 ^ pth part of the whole at 16 oz. per 

 pint) applied directly to an ovum on the point of a needle, was " frequently " sufficient 

 to render it fruitful-^-. The drop spoken of in this experiment was a much less quantity 

 than the grain or minim ; indeed, SPALLANZANI states that it did not exceed the 

 "fiftieth of aline" (? fifth) in diameter. The quantity of fluid obtained by myself 

 from a frog was usually about six minims, and this I mixed with twice its quantity 

 of water, thus making eighteen minims. One drop of this mixed fluid measured, as 

 I found, one-third of a minim, and consequently contained one-third part of seminal 

 fluid, or one-ninth of a minim of the seminal fluid. Yet the result of the employ- 

 ment of one drop of this mixed fluid added to one ounce of water, in which the pro- 

 portion of seminal fluid was then made to be T^Tjth P ar ' f tne whole, did not lead 

 to the same result as the experiment by SPALLANZANI. The difference arose, perhaps, 

 from the operation of two or more causes : first, the much lower temperature of 

 the atmosphere at the time of making my experiment, than at that of SPALLANZANI'S ; 

 next, the diminished efficiency of the seminal fluid, owing to the length of time (two 

 hours) it had been removed from the body. Both these circumstances, but especially 

 the first, as already shown, operate unfavourably in experiments on impregnation, 

 more eggs being fertilized at a high temperature, when the changes go on rapidly, 

 and especially when the seminal fluid has been most recently obtained, than under 

 the opposite conditions. The general results of my experiments, however, may be 

 regarded as quite confirmatory of SPALLANZANI'S more remarkable one, as they prove, 

 like that, that only an exceedingly small proportion of seminal fluid is necessary to 

 fertilize the ovum. 



* Loc. cit., vol. ii. p. 189. 



t Loc. cit., vol. ii. p. 192. There is some confusion of statement in the translation of SPALLANZANI'S work, 

 now referred to, respecting the quantities mentioned by the author, as " pint " is the word used in some pass- 

 ages and "pound" in others (p. 191), apparently synonymously, while the latter is further spoken of as 

 " twelve ounces." G. N. 



