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BIBLIOGRAPHY. 



the surface, I found to be a congeres of exceeding small animalcula of different 

 shapes and sizes. At the same time I look't on a small drop of the green surface of 

 some puddle-water, which stood in my yard ; this I found to be altogether composed 

 of animals of several shapes and magnitudes. But the most remarkable were those 

 which I found gave the water that green colour, and were oval creatures, whose 

 middle was of a grass green, but each end clear and transparent. They would 

 contract and dilate themselves, tumble over and over many times together, and then 

 shoot away like fishes. Their head was at the broadest end, for they stiU moved 

 that way. They were very numerous, but yet so large, that I could distinguish them 

 very plainly, with a glass that did not magnify very much. 



"April 29th, 1696. I found another sort of creatures in the water (some of which 

 I had kept in a window, in an open glass). They were as large as three of the 

 other, with the green border about their middles, but these were perfectly clear and 

 colourless. Then also examining more accurately the belts or girdles of green that 

 were 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 the 

 same use in the litUe creatures : For I found now since April 27. many of them with- 

 out anything at all of that green belt or girdle ; others with it very much and that 

 unequally diminished, and the water filled with a vast number of small aiiimals, 

 which before I saw not there, and which I now looked on as the young animated 

 frye, which the old ones had shed. I continued looking on them at times for two 

 days, during which time the old ones with the green girdles decreased more and 

 more ; and at last I could not see one of them so encompassed, but they were all 

 clear and colourless from end to end. 



"May i8th, 1696. I look't in some of the surface of puddle-water which was 

 blewish, or rather of a changeable colour, between blew and red. In a large 

 quantity 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 were 

 none with those girdles before-mentioned, either of green, or any other colour. I then 

 also 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 never 

 saw the like anywhere but in the Gcnitufa viascnlina of some creatures. Among 

 these there were many of a greenish colour ; but they all moved about so strangely 

 swift, and were so near to each other, that tho' I tried my eyes, I could not distin- 

 guish whether the green colour were all over their bodies, or whether it were only 

 round their middle in girdles, as before, but from the roundness of their figure and 

 their smallness, I judge that they chiefly consisted of the young animated spawn of the 

 kind of animals mentioned already. I found that the point of a pin dipt in spittle 

 would presently kill them all; as I suppose it will other animalcula of this 

 kind." 



The interest attached to the writings upon this same subject of Stephen 

 Gray, published also in the same volume of the ' Philosophical Transac- 

 tions ' for the year 1696, is connected most prominently with the discovery 

 made by this early investigator, that particles contained within a simple 

 sphere of glass, or animalcules contained in a corresponding globule of water, 

 become when viewed under favourable conditions more powerfully magnified 

 than with the assistance of any ordinary bi-convex lens. Several varieties 

 of animalcules were described by Stephen Gray, as examined by him with 

 this most simple optical apparatus, among them being a form, appa- 

 rently the Halteria grandinclla of Dujardin, in association with which he 

 places on record the earliest account of what, while interpreted by him as 

 a possible act of generation, was more probably an instance of the more 

 ordinary phenomenon of transverse fission. A brief abstract, in his own 



