366 Developmental History of Infusorial, Animal Life. 



find the air thoroughly charged with the germs of Uredo (smut) 

 and Penicillium ; and we may readily believe that the same 

 depressing influences that render the human family subject to 

 epidemic disease also affect vegetable life, and the weakly and 

 sickly plant equally with the higher human creature, goes to 

 the wall, and may ultimately furnish the nidus for a colony of 

 parasites. 



In all my collections of rain, snow, and distilled water, 

 animal and vegetable life proceeds to one definite point, and 

 then recedes. I have never found any go beyond Euglena ; 

 and unless some vegetable matter be added to the solution, 

 no higher form of life appears ; on the contrary, a retrogade 

 condition takes place. If some kind of vegetable matter, as 

 hay or lettuce-leaf, be added, then I find, with Mr. Samuelson, 

 rotifers make their appearance — not otherwise. But here, 

 again, we get no further, and the infusion requires a something 

 more to give it a start in life. As might be predicted, these 

 changes are all modified, accelerated, or retarded by the action 

 of light, heat, season, and so forth, and by the presence of any 

 albuminoid material. If fresh-caught rain water be filtered 

 and excluded from atmospheric influences, the appearance of 

 both vegetable and animal life is very much delayed ; but when 

 fresh and clean rain water is exposed to the air, Protococcus 

 quickly makes its appearance, and with it Amoeba ; the cells 

 of the Protococcus soon throw off zoospores, and the Amoeba take 

 possession of the cells and feed upon the zoospores. I mention 

 this latter circumstance, because some observers, both before 

 and since Oienkowski, having doubtless seen the same occur- 

 rences, have stated their belief in the conversion of the contents 

 of the cells of the Protococcus or GJilamydococcus into a free 

 moving mass of amceboid bodies. 



Mr. Carter, well known for his valuable contributions to 

 microscopical science, was one of the first to notice and pro- 

 mulgate this apparently impossible transitory condition of the 

 volvox-zoospores ; but he afterwards saw fit to change his 

 opinion, and in place of looking upon, it as the conversion of 

 the vegetable protoplasm into that of an animal, he now 

 believes that the germ of the Amoeba must have been included 

 in the vegetable cell, or as a parasite made its way into its 

 interior; and remarking upon his first statement, that Aotience 

 are thrown off by Vorticellce, he writes thus : " Seeing, then, 

 the great analogy, if not real identity, that exists between the 

 nature of these organisms, I would suggest that the germ of 

 the Acitence, like the egg of the Ichneumon/idee, becomes 

 encysted in the Vorticellce, and lives upon its host." * 



* Carter. Note on Organization of Infusoria, Ann. Mag. Nat. Hist. 

 Series 3. Vol. viii., p. 207. 



