390 MANIPULATION. 



far that they only resemble small papillse. M. Trembley 

 thought they were very analogous to vegetables, and, to satisfy 

 himself upon this point, he cut several of them in pieces, 

 when, to his great astonishment, he found that each cut portion 

 became a perfect animal. Some of these Polypes having been 

 sent to England, the experiments of M. Trembley were tried 

 with entire success by many of the learned, but more especially 

 by Mr. Henry Baker, who published a book on the subject 

 in 1743, which wiU well repay an attentive perusal. The 

 Hydras are generally found in ponds and rivulets, adhering 

 either to portions of weed or sticks ; they may be readily seen 

 by the naked eye when placed in a clear glass jar. In order 

 to take them home safely, they should be put into clean phials, 

 with a small portion of some aquatic plant, and the phial filled 

 with water ; it should be carefully corked, both to prevent 

 the water from being spilt and the Hydrse from being injiu-ed. 

 At home they should be kept in tolerably large glass jars, in 

 clear river water, with a small plant growing in it ; being very 

 voracious, they wiU require to be often fed, the best animals 

 to give them are the small red-blooded worms (Naiides) that 

 are so common on the banks of the Thames, to the mud of 

 which they impart a red colour, these should be well washed 

 in clean water before the Polypes are fed with them, and 

 the Polypes themselves placed in pure water after every 

 meal; the common water-fleas, in the absence of Naiides, 

 wiU also serve them as wholesome food. The mode of gene- 

 ration of Polypesms by gemmation or budding, and takes place 

 very rapidly, as many as four or five young ones in a week 

 having been known to be produced ; as soon as a young one 

 is provided with arms, it wiU devour the worms with as much 

 eagerness as the older ones. When placed in great numbers 

 in one phial, they do not thrive so well as when they are in 

 small quantities, hence they should be occasionally moved 

 from one jar to another ; this may be readily managed by the 

 end of a quiU, or a fine camel's-hair penciL They are best 

 examined either in one of the troughs shown by figs. 93-4, or 

 in a large animalcule cage, and can be easily divided by a pair 

 of sharp-pointed scissors, like those exhibited at B in fig. 227. 



