187 
was so regular and exact—the longer and more delicate ex- 
tremity so gracefully arched as it flowed after the broader 
head and again straightened out and again bent round to 
form the second loop of the figure of eight, and this motion 
was so continuously kept up—that it was difficult to look 
upon it as due to a mere mechanical fusion of uneducated 
(z.e. not originally developed in connection with this con- 
dition) independent vibratile elements. 
The spermatozoa do not appear to fuse in the way in which 
the ameeboid ‘Schwarmer” of Didymium fuse to form a 
plasmodium, which is the nearest approach to be found to 
such a building up of an organism as the spermatophors 
present. It is probably more correct to suppose that each 
spermatozoon remains perfectly distinct from its fellows, and 
that the unity of their action is due to their uniform con- 
dition and properties and to the uniformly diffused character 
of the stimulus (a chemical one) in response to which they act. 
If this view be correct we may assume similar independence 
for the cilia of all ciliated membranes—a fact already inferred 
from experiment. Did we know of a number of free uni- 
cellular organisms after complete development becoming fixed 
together by a cement to form a secondary organism capable 
of locomotion and possibly of nutrition, we should have a 
parallel to the spermatophors; as it is, they are, I believe, 
the only examples! of the building up of an organ or quasi- 
organism by agglomeration instead of histogenesis. 
1 Such social organisms as Conochilus may be regarded as in a measure 
parallel. But the union in that case is less intimate, aud moreover is a union 
of secondary aggregates. 
VOL. XI.—-NEW SER. N 
