INFUSORIAL ANIMALCULES. 51 



Professor Owen, in his recent learned and able Essay on Par- 

 thenogenesis, refers to the initiative, assumed by the nucleus of 

 Infusoria, in their reproduction by spontaneous fission, between 

 which and the essential contact of the spermatozoon with the germ 

 cell, as a preliminary to the primary process of self-diWsion of the 

 latter, in the course of the development of more perfect animals, he 

 indicates an analogy ; and, after ha^ong completed the comparison of 

 the results in the two cases, goes on to say, " this is certain, that 

 the analogy between these phenomena in the multiplication of the 

 parts of the germ-mass, and those of the nucleus in the multiplication 

 of monads, is so close, that one cannot reasonably suppose that the 

 nature and properties of the nucleus of the impregnated germ-cell, 

 and that of the monad can be different. 



" Therefore, I infer, that the nucleus of the Polygastric animalcules 

 is the seat of the spermatic force ; it can only be called testes, figur- 

 atively, it is the essence of the testis. It is the force which governs 

 the act of propagation by spontaneous fission : and, if Ehrenberg be 

 correct, in viewing the interstitial coipuscles as germ-cells (to which 

 opinion Professor Owen inclines), these essential parts of ova may 

 receive the essential matter of the sperm from the nucleus, which is 

 discharged along with them in the breaking up of the monad, which 

 Ehrenberg regards as equivalent to an act of oviposition ; and im- 

 pregnated germ-ceUs may thus be prepared to difiiise through space, 

 and carry the species of Polygastric animalcules to a distance from 

 the scene of life of the parent." (p. 67, Ed. 1849.) 



Professor AVeisse, of St. Petersburg}!, has detailed some observations 

 (In the " Transactions of the Petersbui-gh Academy," and in 

 Wiegmann's "Archives fiir Faturgeschichte" for 1846,) on the 

 Chlorogonium eucMorum, which he considers decisive of the occur- 

 rence of reproduction by ova, and, also, as demonstrative of some 

 genera of Ehrenberg, being but different stages of development of 

 the same being. Thus, he describes the contained green matter of 

 the Chlorogonium to develope, by spontaneous fission of itself, nu- 

 merous young animalcules, at their first escape, resembling ZfvelJa 

 Bodo, and in further stages, Chlorogonium euchlorum and Glenomorunt 

 ting ens. The young beings escape by a transverse rupture of the 

 parent, wliich, by this form of oviposition, is itself sacrificed, dis- 

 appearing as a shrivelled broken sac. 



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