266 
PACIFIC SCIENCE, Vol. VII, July, 1953 
organs is negligible, as spermatophores pro- 
duced by right and left vasa deferentia reveal 
no dimorphism. 
The living vasa deferentia, freed of the con- 
cealing testes, exhibit spasmodic contractions. 
These serve not only to move the sperm mass 
but to mold it in compliance with the gradual- 
ly changing internal die of the vasa deferentia, 
i.e., first cylindrical, then elliptical, then pear- 
shaped. Serial sections reveal that these grad- 
ual morphological changes are paralleled by 
physiological changes. 
A continuous sperm mass emanates from 
the testis and enters the undifferentiated por- 
tion of the vas deferens. Here the epithelial 
cells secrete a substance of unknown function 
which mixes with the spermatozoa. 
Epithelial cells, isolated at opposite ends 
of the elliptical lumen, produce a new secre- 
tion which at first covers the distal ends of 
the epithelium but later comes to lie con- 
tiguous with the sperm column. This is the 
sperm-column sheath. 
The sperm-column sheath is formed 
through several regions of the vas deferens, 
not solely in the coils of a right-handed helix. 
Longitudinal sections through the region 
of the last compact, left-handed helix fail to 
show the fragmentation of the sperm column 
into separate ampullae. The sperm column re- 
mains continuous, but by-muscular contrac- 
tions of the wall of the vas deferens it is 
forced into continuous sinusoidal curves or 
arches. 
The groove of the now pear-shaped lumen 
deepens, and a new substance is secreted from 
the epithelial cells at its base. This is at first 
thread-like but later thickens in the regions 
between the closing arches. These accumula- 
tions are the precursors of the stalks. The 
muscular activity which closes the arches to 
form the ampullae of sperm is co-ordinated 
with that which lengthens the accumulations 
of this secretion to form the stalks. 
Cross sections through the region of the 
flattened spiral reveal the continued lengthen- 
ing of the stalks and show the origin of a new 
secretion, the precursor of the veil. As the 
lumen of the vas deferens increases in dia- 
meter, the veil and the stalks become more 
elongate, and the ampullae of sperm are borne 
on the distal ends of the stalks. The sperm- 
column sheaths between adjacent ampullae 
are stretched by this process. They become 
extremely thin and, finally, are no longer de- 
tectable, at least not with the staining tech- 
nique employed. 
Cross sections through the enlarged, apical 
portion of the vas deferens reveal a cylin- 
drical lumen distended by fully formed, pe- 
dunculate spermatophores. However, two 
typhlosole-like folds develop which produce 
a mucoid secretion which encompasses the 
spermatophores. 
Muscular contractions of the wall of the 
vas deferens serve now to expel the com- 
pleted spermatophore. When first expelled, 
it is difficult to distinguish the pedestal from 
the veil. If the spermatophore of D. asper is 
allowed to stand in tap water, the veil soon 
disintegrates, leaving the upright stalks with 
their ampullae directly attached to the con- 
tinuous, unsegmented pedestal. Dardanus 
asper is the only hermit crab so far studied 
whose vasa deferentia possess the region for 
the lengthening of the stalks but lack the 
region for the segmentation of the pedestal. 
REFERENCE 
Mouchet, S. 1931 . Spermatophores des crus- 
taces decapodes, anomures et brachyures 
et castration parasitaire chez quelques pa- 
gures. Sta. Oceanogr. de Salammbo^ Ann. 6: 
1-203. 
