THE BEGINNINGS OF LIFE. 239 



taken place in the evolution of Monas lens 1. Cor- 

 puscles were seen to separate from the embryonic 

 aggregations without a flagellum, though they continued 

 to increase in size, and soon developed a vacuole and 

 nuclear particle in their interior. As they enlarged 

 they gradually assumed an oval form, though still re- 

 maining motionless and devoid of cilia. At last, with 

 very little further increase in size, cilia were de- 

 veloped 2 , and the organisms gradually displayed the 

 appearance and locomotory powers which have been 

 attributed by Dujardin to the form which he named 

 Enchelys ovata 3 . 



The organisms previously mentioned have nearly all 

 been minute, and it has therefore been somewhat difficult 

 to trace their early stages. These difficulties, however, 

 gradually vanish when we come to the investigation of 

 the mode of origin of such larger organisms as Para- 

 mecia and Kolpoda. Although their most remarkable 

 mode of origin was fully described and figured by 

 M. Pouchet more than twelve years ago, yet, unfortu- 

 nately, many of our leading biologists have preferred 

 to repudiate his statements, and rely upon their own 



1 See p. 196. 



2 The apparition of cilia is known to be quite sudden in the deve- 

 lopment of the spore of Vaucberia, and also to be sudden during the 

 development of other Infusoria, such as Cienkowski and others have 

 observed. (See Appendix D, p. xciv. note 3.) 



3 To another similar solution of isinglass M. Pineau, mindful of the 

 results recorded by Dutrochet, added a few drops of vinegar, and he 

 says : ' II ne s'y developpa un seul animalcule : mais en revanche elle 

 se couvrit, comme je m'y attendais, d'un foret de moisissures.' 



