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 
