XVII. I then successively opened ten rabbits, on different days, to examine their seminal liquors; the first had not a drop, either in the testicles or seminal vessels. In the second I was no more successful, although I was assured he was the father of a very numerous progeny. I succeeded no better in the third. I then imagined that the presence of the female might be requisite; I therefore put males and females into cages so contrived that it was impossible for them to copulate. At first these endeavours did not succeed; for, on opening two, not a drop of seminal liquor was to be found; however, in the sixth that I opened, a large white rabbit, I found, in the seminal vesicles, as much liquor as could be contained in a teaspoon; this matter resembled calves' jelly, was nearly transparent, and of a citron colour. Having examined it with the microscope, I perceived it to resolve, by slow degrees, into filaments and thick globules, many of which appeared fastened to each other; but I did not remark any distinct motion in them, only as the matter liquefied, it formed a kind of current by which these filaments and globules seemed to be drawn all to one side. I expected to find this matter take a greater degree of fluidity, but that did not happen, for, after it was a little liquefied, it dried, and I could perceive nothing further than what is above mentioned. When this matter was mixed with water, the latter did not appear to have power to dilute it. XVIII. Having opened another rabbit, I only found a very small quantity of seminal matter, which was of a colour and consistency entirely different from the former; it was scarcely tinctured of a yellow hue, and was much more fluid. As there was but very little, I feared it would dry too hastily, and therefore mixed it with water: from the first observation, I did not perceive the filaments I had seen in the other, but I discovered three globules, all in a trembling and restless motion; they had also a progressive motion, but it was very slow; some moved round the others, and most appeared to turn upon their centres. I could not pursue this observation because the liquor so soon got dry.