SPERMATOGENESIS IN MYXINE GLUTINOSA. 183 
few of the cells of each spermatogemma, namely, those near the 
wall of the tubule, undergo a “ chemical dissolution ’”’—that is, 
they lose their original structure, fuse together, and form the 
cytophore (blastophore of Blomfield), The other cells are 
transformed into spermatozoa, and are called by Jensen sper- 
matocytes. These spermatocytes are for the most part uni- 
nuclear, but not invariably ; often they are multinuclear. The 
uninuclear spermatocyte forms a single spermatozoon, and the 
transformation is thus effected. The outer end of the sperma- 
tocyte grows out into a thin filament, the tail of the sperma- 
tozoon; the protoplasm of the spermatocyte collects on the 
outer side of the nucleus, the latter being next to the cytophore. 
The filament after a time can be traced through the protoplasm 
to the nucleus, and, after this stage is reached, the protoplasm 
of the spermatocyte descends along the filament, forming drops 
of various sizes, which are afterwards used up to increase the 
thickness of the tail. 
Now the feature which resembles what I have described in 
Myxine is this:—When the spermatocyte has several nuclei 
each of these may develop into a sperm-nucleus. In this case, 
instead of one filament projecting away from the spermatocyte 
there are several in a bundle, one for each nucleus. The nuclei 
usually remain at their original level, and the multinuclear 
spermatocyte forms a number of spermatozoa. But in other 
cases one nucleus remains in its original position, while the rest 
are carried down the bundle of filaments in the drops of proto- 
- plasm ; some of these nuclei dissolve and disappear, but others 
often develop into sperm-nuclei within the drops, and in this 
way a condition is produced resembling in some degree some 
of the stages I have figured on Plate IV. For instance, in 
Jensen’s pl, ii, fig. 38, there is an elongated bundle of filaments 
connecting three drops of plasma, each of which contains a 
sperm-nucleus. But in Jensen’s cases the points or apices of 
the sperm-nuclei are invariably turned in one direction, towards 
the cytophore, and the base of each is connected with a fila- 
ment which can be traced distinctly through the drop of plasma 
and down the bundle, These conditions do not obtain in 
