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10 BIBLIOGRAPHY.the surface, I found to be a.congeres of exceeding small animalcula of differentshapes and sizes. At the same time I look't on a small drop of the green surface ofsome puddle-water, which stood in my yard this I;found to be altogether composedof animals of several shapes and magnitudes. But the most remarkable were thosewhich I found gave the water that green colour, and were oval creatures, whosemiddle was of a grass green, but each end clear and transparent. They wouldcontract and dilate themselves, tumble over and over many times together, and thenshoot away like fishes. Their head was at the broadest end, for theystill movedthat way. They were very numerous, but yet so large, that I could distinguish themvery plainly, with a glass that did not magnify very much."April agth, 1696. I found another sort of creatures in the water (some of whichI had kept in a window, in an open glass). They were as large as three of theother, with the green border about their middles, but these were perfectly clear andcolourless. Then also examining more accurately the belts or girdles of green thatwere about the animals, mentioned above, I found them to be composed of globules,so like the rowes or spawn of fishes, that I could not but fancy that they served for thesame use in the little creatures : For I found now since April 27. many of them withoutanything at all of that green belt or girdle ;others with itvery much and thatunequally diminished, and the water filled with a vast number of small animals,which before I saw not there, and which I now looked on as the young animatedfrye, which the old ones had shed. I continued looking on them at times for twodays, during which time the old ones with the green girdles decreased more andmore ;and at last I could not see one of them so encompassed, but they were allclear and colourless from end to end."May 1 8th, 1696. I look't in some of the surface of puddle-water which wasblewish, or rather of a changeable colour, between blew and red. In a largequantity of it I found a prodigious number of animals, and of such various bignesses,that I could not but admire their great number and variety but ; among these werenone with those girdles before-mentioned, either of green, or any other colour. I thenalso examined the surface of some other puddle-water, that look't a little greenish ;and this I found stockt with such an infinite number of animals, that I yet neversaw the like anywhere but in the Genitura masculina of some creatures. Amongthese there were many of a greenish colour ;but they all moved about so strangelyswift, and were so near to each other, that tho' I tried my eyes, I could not distinguishwhether the green colour were all over their bodies, or whether it were onlyround their middle in girdles, as before, but from the roundness of their figure andtheir smallness, I judge that they chiefly consisted of the young animated spawn of thekind of animals mentioned already. I found that the point of a pin dipt in spittlewould presently kill them all; as I supposeit will other animalcula of thiskind."The interest attached to the writings upon this same subject of StephenGray, published also in the same volume of the ' Philosophical Transactions' for the year 1696, is connected most prominently with the discoverymade by this early investigator, that particles contained within a simplesphere of glass, or animalcules contained in a corresponding globule of water,become when viewed under favourable conditions more powerfully magnifiedthan with the assistance of any ordinary bi-convex lens. Several varietiesof animalcules were described by Stephen Gray, as examined by him withthis most simple optical apparatus, among them being a form, apparentlythe Halteria grandinella of Dujardin, in association with which heplaces on record the earliest account of what, while interpreted by him asa possible act of generation, was more probably an instance of the moreordinary phenomenon of transverse A fission. brief abstract, in his own