OF CILIATED INFUSORIA 281 



the conditions to which these particular eggs were subjected, the 

 complete transformation of many of them into Cihate matrices and 

 actual CiUates must have been brought about within three days. 



The one set of Hydatina eggs, gathered in the Spring, would 

 appear to have yielded embryo Oxytrichas, as they did at the same 

 time of the year in 1872, and as I subsequently found in 1902 ; 

 while the other set, gathered in the autumn, and exposed to similar 

 conditions, yielded embryo Vorticellas. Why this change in the 

 transformation should have occurred it is impossible to say. One 

 can only conjecture the existence of some very minute difference 

 existing in the ' physiological units ' of the transforniing egg-mass. 

 No difference could be detected in the early stage between the 

 little spherical masses, but when development commenced and 

 the embryos began to revolve within their hyaline cysts, we might 

 feel sure that they were not to issue as Vorticellae. The Hydatina 

 egg produces either the one or the other of these forms — never a 

 mixture of the two.^ 



It remained, then, more fully to study the condition of origin, 

 and to endeavour to trace all the early stages of these remarkable 

 transformations of the Rotifer's egg ; and it was during my 

 attempts in this direction that I discovered the equally remarkable 

 transformation of the entire contents of a Hydatina egg into a 

 single Otostoma, in the manner already described. 



The slight gap still remains, however, in the developmental 

 history of these cases in which a multiple partition of the 

 contents of the Hydatina egg occurs. Yet, although the stages 

 between those that are represented in Fig. 76, D, and the little 

 spheres of Figs. 74 and 77 have not yet been met with, both 

 these changes have several times been found within unbroken 

 Hydatina egg-cases. There is little room for doubt, therefore, 



' It is admitted that metamorphosis from one to another form occasionally 

 occurs among the Ciliata during their stage of encystment (Carpenter on ' The 

 Microscope,' Eighth Edition, igoi, by Dallinger, p. 780) ; and, among such 

 instances of alleged transformation, it is of interest to note that the origin 

 of Oxytrichee from encysted Vorticellae was described and illustrated by Pineau 

 in the ' Annales des Sciences Nat.,' 1848 (Zool.), p. 99, and that of Oxytricha 

 into Aspidisca by Jules Haime in the same publication in 1833 (p. log). Although 

 I had called attention to these transformations in 1872 in "The Beginnings of 

 Life " (vol. ii., p. 494), and had there reproduced figures illustrating such changes, 

 these facts had been lost sight of by me until quite recently. And yet a reference 

 to Note 2 on p. 279 will show, strangely enough, there is some reason for 

 suspecting that at times Aspidiscse may also, like Vorticellae and Oxytrichas, be 

 produced from Hydatina eggs. 



