368 Developmental History of Infusorial, Animal Life. 



The final change and ultimate destination of these curious 

 amoeboid bodies have not yet been made out ; but from Dr. 

 Hicks' s previous observations, made on similar bodies developed 

 from the protoplasmic contents of the cells of the roots of 

 mosses, "which in the course of two hours become changed 

 into ciliated bodies/' he thinks it very probable that this is 

 designedly the way in which these fragile structures are enabled 

 to retain life, and to resist all the varied external conditions, 

 such as damp, dryness, and rapid alternations of heat and 

 cold. ' ' The philosophic mind," observes Mr. Carter, ' ' takes up 

 this line of argument." No one can at first sight witness the 

 changes which take place, almost like a dissolving view, in the 

 protoplasm and chlorophyll of Chlamydococcus, Eudorina, and 

 in that of the cells of the Algce generally, and during which 

 they pass from their original form into that of a rhizopod, 

 without inferring that the form produced is merely another 

 one of that which preceded it, and not an absolute change. 

 Hence my description of the fancied passage of the vegetable 

 protoplasm into Actinophrys." * 



Passing on to the consideration of another stage of this 

 inquiry, we must be struck with c ' the remarkable powers of 

 multiplication by fission and gemmation which many of the 

 group exhibit ; within the last few years the investigations 

 of Muller, Balbiani, Stein, and others have shown that these 

 minute creatures possess a true process of sexual reproduction, 

 and that the sexual organs are those which have been hitherto 

 denominated the c nucleus ' and ' nucleolus/ "f And ulti- 

 mately it will be found that the infusoria have a life history 

 as important as that of the higher classes of animals. Dr. 

 Grant in 1851 recorded the presence of ova in one of the 

 marine sponges (Tethya), thus showing that the Protozoa 

 formed no exception to the other sub -kingdoms of animals in 

 the possession of these essential elements. Five years later his 

 observations were corroborated by Lieberkuhn, in the case 

 of one of the fresh- water sponges. Even then the existence 

 of the generative elements still remained to be demonstrated 

 in the Infusoria. Ehrenberg, it is true, had drawn particular 

 attention to the " nucleus," and some others took note of 

 certain minute filaments, but there these observations rested. 

 Now, however, the whole aspect of this subject is changed, 

 and for the vagueness which, four or five years ago, ckarac- 



* The circumstances unrler which the moss-roots should be placed to show 

 these phenomena, are to float any common moss on a glass of water in the shade ; 

 and when the radicles thrown out are of a considerable length, they may be 

 removed to the slide and examined. Care must be taken not to expose them to 

 too much light and heat." — Dr. Iiicks's Quarterly Journal of Microscopical 

 Science, 1862, p. 103. 



t Huxlev. 



