488 THE BEGINNINGS OF LIFE. 



says 1 : — ' It is not unfrequently seen that some of the 

 cells of the vitelline mass detach themselves from the 

 principal cluster, become clothed with long cilia, and 

 continue to move about actively within the egg until the 

 escape of the embryo. It is even affirmed by Nordmann 

 that they increase by partial subdivision, and that thus 

 from a single detached cell may be produced a cluster 

 having a very definite form, and furnished with long cilia, 

 so as very strongly to resemble a parasitic animal.' 



The independent observations of Dr. Gros have, 

 moreover, established the fact of the occurrence of 

 analogous phenomena amongst the Rotifera. He says 

 he has seen a large egg, which had remained within 

 the envelopes of the parent for about three months 

 after its death, at last begin to produce buds on its 

 external surface 2. These buds continued to increase in 

 size, and after separating became converted into Ciliated 

 Infusoria. And on another occasion, having in his pos- 

 session a number of heterogenetic Rotifer germs ^ which 

 had been corked up in a bottle during a long journey 

 (and thus exposed to very unfavourable conditions). 

 Dr. Gros found by subsequent examinations that these 

 matrices did not go on to the development of Rotifers, 

 as hundreds of them had previously done. He says^ : — . 

 ^ Le vitellus du futur Rotatoire elabora bien encore ses 



^ ' Principles of Comp. Physiol.,' 4th ed., p, 580. 



2 Loc. cit., p. 451, PI. O, figs. 6, 7, 8. 



^ That is to say, a multitude of large Euglenre, very many of which 

 had become animalized and converted into embryo masses, such as 

 usually develop, and formerly had developed, into Rotifers. 



* Loc. cit., p. 329. 



