THE SPERMATOPHORE IN ARENICOLA 1021 
degeneration and phagocytosis. The growth of the giant sperma- 
togonia may be due to the same general causes, the accumulation 
of wastes so changing the osmotic relations between cell content 
and the surrounding medium that an increase in size results, 
either from accumulation of materials customarily excreted or 
through increased absorption from the nutritive fluids that bathe 
the cell. 
THE SPERMATOPHORE DEVELOPED FROM ONE SPERMATOGONIUM 
In the light of these facts regarding the development of the giant 
spermatogonia and those of normal size that float freely in the 
body fluid, it is now worth while to review the formation of the 
ordinary spermatophores—those that are developing from the 
cells in the body of the gonad. A primary spermatogonium 
divides into two, four, eight cells, ete. Some of these cells move 
to the center of the mass and disintegrate to form the blastophore 
whose substance is absorbed as nutrition by the surrounding 
cells and is replaced by more or less excretory matter. Meanwhile 
the mass of cells is migrating toward the margin of the gonad. 
Arrived there, the nearly hollow cluster is given off into the body 
fluid where division of the component cells continues until the 
last generation of spermatogonia is formed. By a slight growth 
the cells are changed into the spermatocytes of the first order. 
The two customary divisions of the cells ensue and the spermatids 
are formed and then change to sperm. Meanwhile the spherical 
mass has changed its shape to the saucer-shaped or lenticular 
mass of the adult spermatophore. 
It may seem an unwarrantable assumption that the ordinary 
spermatophores are the result of the segmentation of a single 
primary spermatocyte. The idea was suggested, rendered prob- 
able perhaps, by the development of the giant spermatogonia. 
It seems proven by the fact that all the cells in a given group 
manifest the same stage of division. It certainly presents a 
striking appearance, (figs. 8 and 9), to have a group of cells—a 
spherical bunch—all in the early prophase, for instance, when the 
adjacent cells manifest no sign of division. The possibility has 
