236 GEO. H. BISHOP 
lation nor the strangulation are apparent. This is possibly owing 
to the slowness of secretion and the small degree of dissolution 
of these short cells. In the distal region of the vas deferens 
adjacent to the gland, the lumen does not always, as elsewhere, 
become clearly defined, but may remain loosely stopped with a 
network of strands and membranes which appear to be remnants 
of the walls of cells that filled this space (pl. 3, fig. 10, and text 
fig. 1, h). These cells become shortened inside their former 
membranes, to form a thin epithelium against the muscular 
layer enclosing the vas deferens. The cytoplasm is dense, the 
nuclei shrunken. The picture closely resembles the final ap- 
pearance of the basal portion of the gland into which this portion 
of the vas deferens serves to conduct the sperm (pl. 3, fig. 10). 
As the drone approaches sexual maturity, this process of 
secretion and reduction of the glandular epithelium commences 
in the tightly coiled epididymis-like portion of the vas deferens 
leading from the testis (text fig. 1, f). It progresses from the 
tips of the cells back to the bases (pl. 2, figs. 5, 5 a, 5 b), and in the 
vas deferens as a whole, from the testis posteriorly through the 
seiminal vesicle. Shortly after the stage at which the cells lining 
the seminal vesicle start secreting, the cells lining the mucous 
gland commence to break down into secretion in the anterior 
end of the gland. The change progresses posteriorly again. 
Thus the cavities of these organs are enlarged through dissolution 
of their walls. This occurs earliest anteriorly, affecting last the 
posterior regions where the contents of both organs are to be 
evacuated into the ejaculatory duct (text fig. 1, h and 7). 
When this process has reached an advanced stage, it leaves 
the walls of the organs characteristically sculptured. In the 
gland (pl. 1, figs. C, D, EZ) the cells entirely disappear anteriorly, 
leaving a very thin membranous bulb-like sac which expands 
with mucous secretion. Posteriorly, the cell nuclei recede toward 
the basal region of the cells, the chromatin shrinks, the cytoplasm 
becomes heavily vacuolated, and the ends of the cells protrude 
into the gland’s lumen in fringed and ragged patches (pl. 3, 
fig. 10, m). Vacuolization at the bases of the cells often appears 
to push whole areas of the cells out into the lumen, leaving their 
