Mr. H. J. Carter on PlcEsconia and Keroua. 251 



leading to the idea that this might be the congress of two indi- 

 viduals originally separate^ has also been noticed ; and to this I 

 might add the possibility of Ploesconia and Kerona, during the 

 early stages of division, as well as the young buds of the latter, 

 being so different as to lead to a false multiplication of species. 

 Another point might be noticed here, viz. the analogy which the 

 disparity in size of the two individuals during longitudinal divi- 

 sion bears to a similar disparity observed in the cell-division of 

 many of the Algae, especially in Cosmarium among the Desmi- 

 diacese — making fissiparation, if we would carry on the disparity 

 or diminution still further, a mere variety of budding. 



Generation by impregnation I have never seen ; neither do I 

 think I have ever seen the congress of individuals of Ploesconia 

 or Kerona preparatory to this ; but I have frequently seen P. 

 truncata more or less charged with globular, refractive, semi- 

 opake, yellowish bodies, of uniform size, as represented in the 

 illustrations (figs. 1 & 2) ; and M. J. Haime has stated that he 

 has seen such bodies issue one after another from the anal orifice 

 in more than one distinct species of Ploesconia, remain stationary 

 for a little, develope a filament from each of their extremities, 

 and then move round rapidly on their axes* : after which they 

 should pass into the form of Oxytricha, preparatory to assuming 

 the higher one of Ploesconia, if the metamorphosis described by 

 this naturalist be common to all the Plcesconice ; but as this has 

 not been proved, and the encapsulation of these animalcules is 

 intimately connected with this process, we will now shortly 

 direct our attention to both. 



Encapsulation. 

 It is a common practice among the Infusoria to surround 

 themselves with a capsule, w^hich seems to be ordained chiefly 

 for self-preservation during want of food or water, after which, on 

 the recurrence of either one or both of these necessaries, they may 

 return to active life either as simple individuals, or multiplied by 

 duplicative subdivision. But this does not appear to be the case 

 with the Oxytrichina, among which, according to M. J. Haime, 

 there is at least one species which undergoes metamorphosis in 

 this way into Trichoda Lynceus, — a process which does not seem 

 improbable, from the insect-like form of Plcesconia, but one en- 

 tirely at variance with the common result of encapsulation among 

 the Infusoria generally. Wishing therefore to witness this my- 

 self, I embraced the first opportunity that was presented to me 

 of collecting a number of Kerona pustulata which were becoming 

 encapsuled under my eye, and transferring them to a watch- 

 glass for observation, where, after a certain time, and under cer- 

 * Ann. (les Sc. Nat. /. c. p. 131. 



