48 Proceedings of the Royal Physical Society. 



appears ; but in about fourteen days there are seen a number 

 of small transparent vesicles little larger than the chlorophyll 

 granules in the interior of the body. These vesicles increase 

 in size, till at last the parent animal bursts, and liberates 

 from six to ten spherical bodies, with a large nucleus occu- 

 pying the centre of each, and two or three chlorophyll 

 granules between the nucleus and the cell-wall. In a day 

 or two the spherical body becomes capable of expanding and 

 contracting slightly ; and at one end several cilia appear, 

 which is the oral extremity. The animals, increasing in 

 size, soon become identical with the animals from which we 

 started. When they appear to be full grown, they begin to 

 show symptoms of division, which takes place in the direc- 

 tion of the long axis of the body. This division goes on 

 with great rapidity ; and as each secretes a small quantity of 

 the gelatinous substance, a mass containing thousands of 

 Ophrydia is soon formed. The secretion of a small gela- 

 tinous investment by each also shows the manner in which 

 the cellular appearance of the mass is formed, by gritty 

 particles getting between the joinings. 



The nucleus of the Ophrydium has been described as 

 composed of numerous small vesicles joined together in a 

 moniliform manner ; but this may be accounted for by sup- 

 posing that the animal was observed when the nucleus had 

 broken down, and liberated the spherical vesicles into the 

 body cavity. This process is exactly similar to the endo- 

 genous multiplication of cells. 



The liberation of the vesicles in all the specimens of 

 Ophrydium examined was effected by the entire disintegra- 

 tion of the parent animal. This seems to differ from the 

 observations of Dr Balbiani, who observes, " We see, there- 

 fore, that while in some Infusoria a nucleus appears de novo, 

 after each reproductive act, to replace the old ovary, which 

 has left no trace of its presence, in others it is formed anew 

 from those parts of the same organ which have not been 

 concerned in the production of generative elements. This 

 reconstruction of the sexual apparatus seems to show, that 

 oviparous propagation does not assign a term of limit to the 

 propagation of these beings, as occurs in the case of a large 



