200 PHILOSOPHICAL TRANSACTIONS. [anNO 1685. 



if they had been in the uterus; also that conception in females is not always 

 made immediate post congressum, but sometimes p or 10, or more days after it, 

 if one of the animals can then find the punctum or proper place for its nourish- 

 ment: and lastly, that the uterus may not be fit for the reception of animals at 

 one time, though before 2 or 3 days are passed, it may become perfectly 

 capable. 



I know my opinion about generation has been rejected by several persons, 

 some whereof being skilled in anatomy have affirmed to me, that the semen 

 masculum never comes into the uterus; that it is never to be seen in that place; 

 and that it is nothing but a vapour which causes fruitfulness. But I am not of 

 these men's minds ; for it seems plain to me, that the parts are proportioned by 

 nature for carrying the semen into the uterus. And therefore wolves, foxes, 

 and dogs are fastened; and though the dog at first sheds a little thin clear 

 moisture, yet that is not a true semen, for I could not find any animals in it. 

 But as he is fastened, there drops very leisurely a little semen, which is white, 

 by reason of the great number of animals contained in it : and this would not 

 reach the uterus, by reason of its coming so slowly, and of the swelling of the 

 penis, unless the dog were fastened. I remember that Dr. Grew, in a letter to 

 me, used some words to this purpose : Harvey in his book de Gen. Animal, 

 denies that he ever found in the uterus anatomised immediately after concep- 

 tion, the semen masculum. And Dr. De Graaf, in his book de Part. Muliebr. 

 Gen. inservientibus, constantly asserts, that the semen masculum is nothing but 

 a vehicle of a certain volatile salt, or such like spirit, conveying to the egg of 

 the female a contactum vitalem. But though a late writer has reckoned up the 

 authorities of 70 persons, who have asserted the same opinion, and that of the 

 ovarium, yet I think they have been all mistaken. As will appear by the fol- 

 lowing trials. 



A bitch was delivered to me after she had been once lined. The next day 

 she was lined again at 8 A. M. in my presence, and again at 2 o'clock P. M. 

 whereupon I caused her to be killed, by running an awl into the medulla spinalis 

 near the head. As soon as she was dead, I bound her legs to a table, and 

 opened the vagina where I found a white substance, which I took out, and 

 viewed with my microscope, discovering it to be nothing but scales, of that sort 

 which cover the inside of the vagina, lying in a clear thin liquor. Afterwards 

 I opened the middle of the cornu on the left side, which was about 3^ inches 

 long, and as thick as a good quill, as at K, pi. 5, fig. 6. Had I only looked 

 with my naked eye, I should have said there was no semen of a dog in it, but 

 when I made use of a very good microscope, I saw to my great satisfaction, a 

 very great number of the living animals of that semen. I then opened the 



