Mr. II. J. Carter on the Organization of Infusoria. 229 



nucleus, fixed in a spherical capsule, surrounded by a zone of 

 granular plasma (?) (fig. 95) *. This, as will be seen hereafter, 

 is very like the state of the nucleus in the rhizopodous cell of 

 the protoplasm of the Characese, when the former is undergoing 

 reproduction. 



With reference to the organs of generation in the other Infu- 

 soria, I can state no more than that although there is a fusiform 

 nucleus in Otostoma^ I have also constantly seen a bunch of string- 

 like filaments floating about its interior, which appeared to be 

 attached near the buccal cavity ; and although I could make out 

 nothing more, I could at the same time only liken these to the 

 generative apparatus in the Planaria mentioned, which floats 

 round the buccal cavity and upper part of the membranous 

 stomach in a similar manner. 



Impregnation. — In Amoeba and in Actinophrys a union of 

 two individuals is not uncommon, and many have noticed this 

 in the latter. It has occurred to me, also, to see it in a species 

 of Amoebay which, from its circular form, and the prolongations 

 only taking place from one point of the circumference, appeared 

 thus to present an anterior extremity, by which several pairs 

 of the group were united (Plate V. fig. 17) ; and on one occasion 

 two separated under my eye, when an attenuated prolongation 

 of one seemed to be drawn out through a thick prolonged por- 

 tion of the other (fig. 18). More convincingly and frequently, 

 however, this union was observed in a group of Euglypha, where 

 the anterior extremity of the body is distinct (figs. 34, 36). Here 

 the protruded parts, after having been united for some time, 

 began to separate by constriction at the point of contact, which, 

 soon diminishing to a mere mucous thread, became smaller and 

 smaller, and more elongated, as the two individuals, retreating 

 from each other, withdrew themselves into the bottom of their 

 test respectively, from which they appear on such occasions never 

 again to emerge. Lastly, in a group of Euglena deses, several 

 couples appeared united by the tails, not only to one another, 

 but fixed to the watch-glass at this point, where they continued 

 until each sank down, close to the other or separate, into cap- 

 suled forms filled with ovules, — a state which appeared so much 

 the more to be the result of impregnation, from the number of 

 couples thus united presenting every stage of ovigerous develop- 

 ment in their interior, from mere molecular sarcode to repletion 

 with full-formed ovules (figs. 49, 52). It is not an uncommon 

 thing to see, among a group of Euglena agiles (H. J. C), indi- 

 viduals chasing each other, becoming united head to head, head 

 and tail, or tail to tail, and then separating with difficulty by a 



• * Op. cit. tab. 5. figs. 26-28. 



