OF ANIMALCULES. 16/ 



with the lower extremity of the alimentary canal, with 

 {t t), two elongated bodies resembling the milt of a fish, 

 which Dr. E. denominates testes^ and with a muscular 

 changeable body {g). 



When this creature is about to deposit its eggs, it at- 

 taches itself as usual by the tail to the sides of the glass 

 or other vessel in which it is kept, and near to the sur- 

 face of the water. The eggs are of an oval figure, and 

 twenty or thirty are usually seen in a cluster, though they 

 are produced separately : they vary in size from 1- 1000th 

 to 1 -200th of an inch, and are of a brown colour, with 

 different degrees of opacity. In the darker eggs no trace 

 of motion can be perceived, but in the lighter the embryo 

 is often seen to move vigorously, and the rotatory cilia of 

 the young are distinctly observed vibrating within the 

 shell. 



396. VoRTicELLA rotatoria (Rotifer vulgaris, Shrank 

 and E. — Fiircularia rediviva, Lamarck.) — The common 

 wheel Animalcule, — This curious creature, the astonish- 

 ment and delight of all its observers, has been already 

 described in the ^^ Microscopic Cabinet,'' chapter VI., 

 where two plates, besides wood- engravings, are em- 

 ployed in its illustration 5 yet the beauty and com- 

 plexity of its structure incline me to make some few ad- 

 ditional remarks, although I must refer the reader to 

 the above for more general information. In the speci- 

 mens drawn in plates 5 and 6, and at page 65, of the 

 " Cabinet," some portion of its internal structure is unde- 

 fined, in consequence of the colouring of the creature. 



