yorticellina.] THE infusoria. 261 



ova, are to be seen, but the seminal gland, self-division, and 

 growth of gemmae, have not been observed. In water this 

 creature often covers grasses and rushes with a beautiful 

 green layer. Length 1 -240th ; stalk five times the length 

 of the body. 



401. VoRTiCELLA patelUna (M.) The dish-shaped Vorti- 

 cella has an hemispherical body, campanulate, the frontal 

 portion very much dilated, and the margin of it expanding 

 greatly, and often reflexed. Length 1 -480th; stalk about 

 seven times the length of the body. 



402. VoRTiCELLA cotivalaHa (V. craterformisy citrina, 

 gemella, globularia, Maris, nasuta et truncatella : Enchelys 

 fritillus, Trichoda gyrinus, M.) has an ovate, conical, 



campanulate body, the frontal portion dilated, and its 

 margin slightly expanded. It is annulated, and of a 

 hyaline or whitish hue. This appears to have been the 

 first infusorial animalcule discovered. Leeuwenhoek, the 

 discoverer, found it in stagnant rain-water, at Delft, in 

 April, 1675. It is found in considerable abundance, upon 

 the surface of vegetable infusions, with V. microstoma, 

 from which it is distinguished by its broad front, which 

 gives to it a bell-shaped or campanulate appearance. 

 Cams, in 1823, represented it as arising from sponta- 

 neous generation (generatio spontanea) in oil. The 

 medium was an accidental mixture of oil colour and spring 

 water. Ehrenberg remarks, the appearance arose in a 

 very natural way. It has been described under various 

 names by different naturalists. Ehrenberg gives 38 re- 

 ferences to different works treating on it. Figure 237 

 (plate V.) is a group of three, with the pedicle of another, 

 to shew the manner in which it deflects it spirally. 



