G46 



PROTOZOA. 



Class I. INFUSORIA. 



'fills Class of AiiiiiKils is one of tlie revelations of the niioroscope wliich is calculated to fill 

 the iiiiiul with profouiul astonishment at the fullness and infinitude of animal life. Though gener- 

 ally so minute as to elude the unaided vision, they are still of various forms and sizes, and are 

 arrangt'd by naturalists under various subdivisions. Nearly every drop of water on the surface of 

 the ulobe appears to contain thorn in greater or less profusion ;* some of them are not more than one 

 two-thousandth of an inch in length, and even the generality of the race do not exceed one-fiftieth 

 of an inch. Eight hundred thousand millions may be contained in a cubic inch of water, and 

 a thousand millions in a single drop of water ! Nevertheless, these creatures live, and have their 

 being, and are marked with habits and capacities well worthy our consideration. They also 

 seem to perform an immense work in the economy of nature. The progeny of some species 

 amount to two hundred and sixty millions in a single month, thus supplying an incredible 

 amount of food to the multitudinous generations of minute animals that inhabit the waters of 

 the earth. We shall, however, be able to notice only a few of the more remarkable species, in- 

 cluded in the orders which compose this class — Stomatoda and Astomata. 



ORDER 1. STOMATODA. 



This term is derived from the Greek, stoma, a mouth. The order includes several families, all 



of which are distinguished by the possession of a mouth. 



THE MONADID^. 



These consist of rounded or oval animalcules, each of which 

 possesses a mouth, furnished wdth cilia, through which it is 

 able to introduce into its substance, particles of solid matter 

 which serve for its nutrition. One species is called the 

 Twilight Monad, Monas crepusculuni, from its being con- 

 sidered as forming the unit of existence, the point from whence 

 the glimmering spark of life first emerges out of the darkness 

 of nonentity. It consists, says Gosse, " of a tiny speck of pel- 

 lucid matter, rounded in form, and supposed from its move- 

 ments and from analogy, to be furnished with a single cilium, 

 by the lashing action of which it rows itself through the 

 water. No words can convey an adequate idea of the size 

 of an animal so minute as this ; but the imagination may be 

 assisted by supposing a number of them to be arranged side 

 VARIOUS FORMS OF ANIMALCULES MAGNIFIED by slde in coutact with each other, like the beads of a neck- 

 Fig, i, j/b/w^f*; 2, Forms assumed by lace, when twelve thousand of them would go comfortably 

 the Amoeba ; 3, Flask Animalcules, En- vi • +i i 4.1, i« • ^ ■ \. tt x i v 1 



cMis; 4, Actimph-ys sol; 5, EugUna '"^^'''^ ^^® ^''"S"^^ ""^ ^ ^^"§"^® '"''^- ^^ '''^ ^^^^ ^ ^''''?^^ 

 viridis ; 6, Gonium pectorale ; 7, Trache- of leaves of the common sage, for example, or a few twigs 

 lias anm; 8, Paramecium aurelia; 9, of hay, and, tying them into a bundle, suspend them in a jar 



jVavicula;10,ribrioSviriUum: 11, Vorti- e \ 11 -xi xxx -x iivx 



cella Mentor ^^ water, allowing the contents to remain untouched, but ex- 



posed to the air, some interesting results will follow. If 

 we examine it on the second day, we shall find a sort of scum coverinir the surface and the 



"It is a great error, which the common style of exaggeration in writing on such subjects has brought about, and 

 which great numbers of people believe, that all water contains animalcules, and that every drop of water is filled 

 with animal life. So far is this from the truth that, in ordinary clear water taken from the middle of a well or from 

 the center of a spring, there is but little chance of finding animal life ; and any creature discovered by the micro- 

 scope in such water must be regarded as an estray from the mossy sides of the spring, or the chinks of the stones, and 

 of the bucket in the well. But it is equally true that in the moss at the sides of the clearest spring, myriads of ani- 

 malcules live, and a drop of water scraped with the green ooze from the old oaken bucket, overflows with animal 



