412 
EDWIN S. GOODRICH. 
corresponding to the second and third pairs of sperm-ducts, 
but it is a remarkable fact that I have never found true 
spermatozoa belonging to these segments. However, there 
are organs which must be considered as homologous with 
testes, although not producing true spermatozoa. Occupying 
the same position as the testes in segment 5 are found, in 
segments 6 and 7, two cords of cells starting from the 
coelomic epithelium on the septa between the segments 5 
and 6, and 6 and 7 (figs. 19, 26). They enlarge behind into 
masses, soon breaking up into spherical cells, which float off 
in the coelomic fluid. Segments 6 and 7 always contain a 
large number of these rounded cells, very conspicuous in the 
living worm owing to their refringent contents, especially in 
large and ripe specimens. But the cells in segment 6 differ 
from the cells in segment 7, those in the first of these 
segments being more spherical and containing numerous 
minute refringent granules (fig. 19a), while those in the 
seventh are less regular in shape and hold only a few large 
oval granules (fig. 19b). We have, then, a very remarkable 
state of things in the adult male Nerilla — namely, three con- 
secutive segments provided with testis-like organs producing 
different kinds of floating cells; in the first true spermatozoa, 
in the second cells with small granules, and in the third 
cells with large granules (dia grammatically shown in figs. 19 
and 20). The cavity of each of these segments is shut off by 
complete septa, and from each two ducts lead to the common 
pore ; but whether the granular cells are really carried out to 
the exterior I have not yet ascertained for certain. It may 
be that they contribute to the formation of the seminal fluid. 
It might be thought that the males I have examined were 
exhausted, that the sixth and seventh segments produced 
spermatozoa first, and that, after these had been expelled, 
the granular cells took their place. But there is no evidence 
to support this view. The granular cells are found in small 
as well as in large individuals. 
