234 GEO. H. BISHOP 
after the drone is of superficially mature appearance, and con- 
tinues to the fifth day of imaginal life at least though the drone 
is probably not functional until later (table, p. 252) The contents 
of the organs, their mode of responding to such stimuli as cause 
extrusion of the penis, and the motility of the sperm are all 
correlated specifically with the age of the drone. The age can 
be determined by superficial examination of the degree of degener- 
ation of the testis. This undergoes a gradual shrinkage, and 
changes from a creamy-yellow color and bean-like shape, of 
5 mm. length, to greenish-yellow color, flat triangular shape, 
and 1.5 mm. length. This change in the testis is a convenient 
measure of the histological development, size, and maturity 
of the other organs. 
A. Histology and anatomy of male organs 
The vas deferens, seminal vesicle, and mucous gland are 
derived from a common fundament; when mature they are 
histologically similar; they perform their functions of secretion 
and contraction in essentially the same manner. A detailed 
description of the histological elements and of their physiological 
characteristics may apply, therefore, to all the parts derived 
from this fundament taken together. 
The two histological elements chiefly concerned here are the 
columnar cells of the glandular epithelium which forms the 
continuous wall of the lumen of these organs and the muscle 
layers that continuously envelop them. Concerning the glandu- 
lar cells, the important considerations are the manner and nature 
of their secretion and the qualities of the product; concerning 
the muscle layers, their arrangement and the effect of their 
contraction upon the contents of the organs at different stages 
of development. 
1. The glandular epitheium. The glandular cells (pl. 2, figs. 
5a, 6a) are extremely long and narrow, twenty or thirty times 
as long as thick, with oval nuclei, one to each cell, scattered 
through the basal half of the cell layer. The nuclei are so large 
relatively to the diameter of the cells that the oval form may 
be assigned to compression by the cell walls. Their scattered 
