of the Trichodina pediculus (?). 273 



sketch of the animalcule at this stage of development, it happened 

 unfortunately, that, in the instant, the first vesicle had detached 

 itself and floated away, leaving the second free at the margin. 



Moreover, it is to be noted, that, after the disappearance of 

 this first sac, two spherical granular bodies similar to those I had 

 thought to be present in it were still perceptible, occupying the 

 same relative position to one another (fig. 12). 



Watching the progress of the second sac up to eight o'clock, 

 I saw it gradually make its way outwards, leaving more and more 

 of the parent-being free. The latter still presented numerous 

 small globules and greenish particles. Having subsequently 

 made compression, the process of detachment was hastened, and 

 at length completed, the second sac becoming independent. How- 

 ever, this interference with the natural progress of development 

 seemed to arrest its activity, for the detached bud showed no in- 

 dication to move away, and the parent animal was left broken 

 and misshapen, but still retaining its green globules and particles 

 (%• 12). 



Remarks. — The process of development above described may be 

 called one of internal gemmation, and is distinct from that of 

 spontaneous fission, as detailed by authors, although in some of 

 its phenomena and phases it may resemble it. M. Dujardin 

 would restrict the modes of propagation of the true Infusoria, or 

 so-called Polygastrica, to that by spontaneous fission, and, occa- 

 sionally, by gemmation. But in the animalcule observed by me, 

 we certainly find another mode in operation, more akin to gene- 

 ration by ova, which Ehrenberg considers to occur, although that 

 most able microscopist would seem to have founded his opinion 

 on other observed appearances, interpreted by Dujardin as due 

 to the process of ' diffluence.' 



It would have been very gratifying to me to have been enabled 

 to follow the detached bud, and to have watched the changes it 

 might have undergone. I have since met with diaphanous vesicles 

 similar in character, devoid of any distinct nucleus, containing 

 only some small particles of greenish matter, but have never been 

 able to discover a very decisive progress in their development. 

 However, this fact is certain, that the product of the animalcule 

 observed did not partake of its distinctive characters, but was 

 merely a simple non-ciliated cell. Such characters truly might be 

 subsequently developed in it, or in another being derived from 

 it, in accordance with the phenomenon of ' alternation of genera- 

 tion ' of Steenstrup, or with the truth-bearing hypothesis of Prof. 

 Owen, of an active c spermatic force/ 



It being much more my purpose in writing this paper to re- 

 cord an observation than to speculate upon it, — leaving the latter 

 to others more capable than myself, — I shall conclude by merely 



