xlii 
THE VOYAGE OF H.M.S. CHALLENGES. 
If in this stage the gonophore be laid open, and the protoplasm masses, whose 
formation we have been tracing, be liberated under the microscope, we shall often 
succeed in witnessing very minute processes of clear protoplasm, which have become 
developed over the surface. These, however, are not permanent structures, and they 
will often, while the object continues under observation, become entirely withdrawn. 
They are in fact true pseudopodia, and are probably employed in the nutrition of the 
masses from which they arise. 
The contents of the gonophore, however, are destined to undergo further change 
before the period of their liberation has arrived. The separate protoplasm masses 
increase in size, the residual matter which had surrounded them has disappeared, 
having probably afforded material for their nutrition, they begin to coalesce with one 
another, and there is ultimately formed a single large plasmodium which entirely 
fills the cavity of the gonophore. When this plasmodium is examined under the 
compressorium, the same nuclei which had hitherto characterised the products of the 
coalescence of the ova are seen to be scattered in great number through its substance. 
These nuclei, however, have already begun to suffer a change, for while in some the 
nucleolus is still distinct, in others it has quite disappeared, and while in some the 
contents consist of a minutely granular matter, in others they are quite homogeneous. 
When the separate protoplasm masses have all united with one another, or a little 
before they have become so completely fused together as to have their original 
distinctness entirely lost, the time has arrived when the contents of the gonophore are 
to be expelled. Its walls, which present the remarkable character of having a strong 
muscular layer developed in them, now begin to contract on the contained plasmodium, 
which is thus gradually forced out through the summit, of the gonophore. By the 
continued contraction of the walls of the gonophore, the plasmodium is at last entirely 
expelled, completely enveloped, however, in a transparent structureless membrane. 
The empty gonophore may now be seen retracted in the form of a shallow thick -walled 
cup with everted edges, upon the summit of its short peduncle. 
The liberated plasmodium closely enveloped in its structureless capsule is of a 
nearly spherical form, and now lies upon the retracted gonophore. It does not, 
however, continue long in this position, for the function of the claspers is soon brought 
into play. These remarkable bodies, which have no representative in any other known 
Hydroid, are long, cylindrical, very contractile, tentacle-like organs which spring from 
the body of the hydranth. Each is slightly enlarged towards its distal extremity 
where it terminates in a sucker-like disc. One of these claspers (sometimes two or 
even three) now stretches itelf out towards the liberated plasmodium, and as soon as it 
reaches it, it becomes attached by its sucker-like extremity to the capsule and then by 
strong contractions pulls the plasmodium still enveloped in its capsule away from the 
remains of the gonophore on which it had lain. 
