258 E. A. ANDREWS 
That this mass is run in under pressure seems indicated by the 
way it tends to flow out at the narrow slit leading up from the 
tube into the groove and by the form of the sperm mass that 
tends likewise to copy the shape of the cavity that is filled, being 
pointed toward the slit (fig. 14). In successive sections this sperm 
mass 1s found all along the length of the groove, always in the 
bottom of the tube only, while the enveloping secretion for the 
most part disappears. Thus in the fig. 15 from the level 10, 
where there are still some secretion tubes coming through the 
heavy shell of the median mass, (fig. 10) there are a dozen or so 
sperm enclosed in the minute tube together with very little secre- 
tion and the sperm seem to come into contact with the shell. 
At this level, however, the thick and well-calcified shell (fig. 10) 
is covered by a thick layer of horny substance that makes the 
shelf and continues on up the face of the external mass bounding 
the groove, (fig. 15). The discharge of the milk-white sperm from 
the tip of the canula, (figs. 5, 6 and 13) was seen in some males 
separated from females in conjugation. 
The anatomy of the stylet thus shows it to be a more refined and 
specialized tool for sperm transfer than had been expected. It is 
essentially a very fine tube receiving sperm at its larger base and 
discharging it at its attenuated tip; but it has walls that give it 
great strength and rigidity while allowing the tip some elasticity. 
Moreover the receiving part of the tube is provided with glands 
of problematic value. 
In looking for further light upon the nature of this sperm trans- 
fer organ we turn to its development in the individual. 
ONTOGENY OF STYLET 
We find that in Cambarus affinis the first and second larval 
stages are externally alike, in both sexes, while the third shows 
the male openings on the fifth legs, or the female on the third 
legs. In the first stage, there are no abdominal appendages on the 
first somite and but a crowding of epidermal nuclei under the 
shell where the appendage will be. In the second stage, these 
appendages are slight papillae. These indifferent stages are fol- 
