116 
THE ORGANIC CELL 
A great host of unicellular forms could be quoted as examples, 
showing every gradation as regards size of the conjugating 
cells — from those in which sperm and germ are equal, to such 
a form as Volvox, in which there is a marked difference in 
size between the oosphere and the antherozoid, the egg-cell 
being large, heavily laden with food material and incapable 
Volvox. 
Showing the small ciliated somatic cells, and eight large germ cells. (Drawn 
from life by Emerton.) 
of movement, while the antherozoid is much smaller, its 
cytoplasm is greatly reduced, and it is highly mobile. 
In multicellular forms there is a continuation of the same 
phenomena. The egg contains a large supply of food stuffs. 
For its development conjugation with a sperm cell is necessary. 
The sperm cell is the spermatozoon, which is exceedingly 
minute in size, consisting of a nucleus, centrosome, and a very 
small amount of cytoplasm, which is differentiated into an 
organ of locomotion in the form of a tail. It is quite evident 
there is a physiological division of labour between the two 
conjugating cells. The egg from its size has lost the power of 
