VOL. XXII.] PHILOSOPHICAL TRANSACTIONS. 571 



cod-fish ; but could not bring the animalcula to such a position as to have a full 

 and perfect view of them ; not only by reason of their wonderful sinallness, but 

 also because their bodies are so tender and soluble, that when I diluted the 

 spawn with rain-water, in order to separate them from each other, and after- 

 wards exhaled the watery parts, their little bodies burst in pieces ; after which I 

 could only see the tail ; these oval small parts I concluded to be the animalcula 

 turgid with water, and burst to pieces, and these broken parts seemed to be 

 four times as large as the entire body of one of them. 



In another place, where a great many of these animalcula lay together, they 

 appeared like bright bubbles, lying in a watery slimy matter, inclosed in a cir- 

 cular pellicle or membrane. 



I have observed more than once the animalcula in several cod-fish, even in 

 the male seed, where I little expected to find them living, because the seed was 

 not newly come from the fish, but squeezed out of the vasa deferentia, and 

 exceedingly thick, and have discovered an infinite number of exceedingly small 

 creatures alive and swimming together, and I viewed them often so long till the 

 liquid matter in which they swam was quite exhaled, and the animalcula dead ; 

 and where they were a little dispersed, they were burst asunder ; but where 

 they lay thicker and closer together I could not perceive the broken pieces of 

 their bodies. 



Whilst I observed these animalcula, without putting them into any liquor, 

 they seemed smaller than when I viewed them in a round glass tube. That I 

 might represent their smallness as Well as I could, I took one of the hairs of 

 ray head-, and placed it near those creatures; when it could easily be judged 

 that go of them did not exceed the diameter of the hair ; but to keep within 

 compass, I will only say, that as the air appeared through the glass to be an 

 inch broad, so at least 6o of those animalcula would easily lie within its dia- 

 meter. This being supposed, and their bodies being allowed to be, as they 

 are, spherical, then 216,000 of them are equal to a globe, whose axis does 

 not exceed such a single hair's breadth. As for the tails, I judge them to be as 

 long as the tails of those animalcula found in the male seed of a ram. One 

 cannot easily perceive these tails, and I must own that I could not see the 

 tips or smaller end of them ; for as all tails are thickest in that part which im- 

 diateiy joins the body, these were not as thick, even there, as the tips of 

 the tails of the above-mentioned animalcula. 



As there is a vast difference in the solidity or consistency of the skin, flesh, 

 and bones of a cod-fish, when compared with the same parts in a sheep, or 

 other land animal, so I observed likewise, that the same may be asserted of the 

 several kinds of animalcula found in the male seed of different animals. For, 



4 D 2 



