Spermatophoric Mass of a Nephropsid — Matthews 119 
Fig. 7. Camera ludda drawing of a portion of a cross section of the distal region of the vas deferens showing: 
a, sperm mass; b, spermatophoric sheath; c, homogeneous matrix; d, space; e, epithelial cells;/, muscle layer. (90X) 
of the vas deferens reveal what appears to be 
a sperm mass (Fig. la) surrounded by an ex- 
tremely thick spermatophoric sheath {b, c). 
The reason for this misinterpretation lies in 
the fact that the sheath-forming secretion has 
the same consistency and staining properties 
as the matrix (Fig. Ic ) ; both have an affinity 
for the cytoplasmic stain. Careful examination 
of the cross sections through this region, 
however, reveals a distinct diastem separating 
spermatophoric sheath {b) from matrix (c). 
Proof of the individual identity of these two 
secretions is further attested by placing the 
contents of the dissected, distal vas deferens 
in 0.1 N KOH. The outer matrix is readily 
soluble and soon disappears, whereas the inner 
spermatophoric wall, being less soluble, re- 
mains to disclose a highly coiled, continuous 
spermatophore. 
The increased thickness of the muscular 
coat (Fig. if) probably plays a part in the 
expulsion of the spermatophoric mass during 
copulation; but whether it serves to segment 
the otherwise continuous spermatophoric tube 
into ampules is conjectural, since females with 
naturally occurring spermatophoric masses 
were not available for study. It seems very 
likely, however, that in either case the sper- 
matozoa, encased in a spermatophoric sheath 
and enveloped in a hardened matrix, would 
require a mechanical method for their 
liberation. 
Further indirect evidence in support of ex- 
ternal fertilization is obtained on examination 
of the female, for although a large seminal 
receptacle is present, it is found not to con- 
nect internally with the female reproductive 
system, and probably serves as a receptacle 
on which to receive the spermatophoric mass 
of the male. 
Because this mass becomes hard in a few 
hours when experimentally placed on glass 
plates immersed in sea water, it appears rea- 
sonable to assume that in naturally formed 
spermatophoric masses of E. occidentalis a sim- 
ilar change in consistency would necessitate 
mechanical liberation of the spermatozoa. 
SUMMARY 
The male reproductive system of the ho- 
marid-like, nephropsid lobster Emphmetopus 
occidentalis (Randall) is dissected and figured. 
Cross sections throughout the testis reveal 
follicles in various degrees of maturity. An 
immature follicle, by mitotic division of the 
cells of its germinal epithelium, becomes 
filled with primary spermatocytes. These cells, 
by both heterotypic and homeotypic divi- 
sions, form spermatids. 
Concurrent with the formation of primary 
i 
