FOREST IMPORTANCE OF MYELOPHILUS MINOR HART. 
225 
side of each testis a duct passes, known as the vas deferens. The two vasa 
deferentia unite and form a common duct which .leads to the penis. 
About halfway between each testis and the union of the vasa deferentia 
each duct is much swollen, appearing in side view as a lens-shaped receptacle 
known as the seminal vesicle. Two blind diverticula, — the accessory glands— after 
uniting with each other, open into the vasa deferentia just before the latter 
swell out to form the seminal vesicles. 
The chitinous supporting part of the penis consists of fork, ring, and sheath. 
The ring is circular in shape, and partly surrounds the sheath of the penis. The 
sheath is made up of a sheet of chitin, the edges of which overlap at the sides. 
The sheath anteriorly is prolonged into two rods known as the femora. The lower 
part of the common vas deferens passes between the femora, through the ring, and 
down the centre of the sheath. 
Repeated dissections of the male reproductive organs were made ; the struc- 
tures were examined in various media. In this way the male reproductive 
organs of minor and piniperda were compared. No reliable differences were 
observed in the softer parts, but the chitinous fork afforded an excellent means of 
distinguishing the males of the two species. 
The fork of M. minor (F., fig. 16) is visible to the naked eye. It is a stout 
chitinous rod, breaking up at the posterior end into two short branches which 
are slightly curved. Anteriorly it ends in a blunt, triangular-shaped knob. In 
a few cases this triangular knob was prolonged on either side into short thin 
branches, which were slightly curved. 
Compared with this, the fork in M. piniperda is not nearly so stout (fig. 17). 
Posteriorly it diverges into two short branches which are mpre curved. Anteriorly 
the main rod is bent almost at right angles, and it tapers gradually to a point. 
The ripeness or unripeness of the male reproductive organs may be thus dis- 
tinguished under the microscope : — 
U nripe. 
Testes white and without spermatozoa. 
No spermatozoa in the vasa deferentia. 
Seminal vesicles small. 
No spermatozoa in the seminal vesicles. 
Accessory glands short and thin and 
only slightly developed. 
Ripe. 
Testes yellowish and with sperma- 
tozoa. 
Seminal vesicles small and full of 
spermatozoa. 
Accessory glands greatly lengthened 
and swollen and with spermatozoa. 
I verified the main points in the above differences, the variation in size of the 
seminal vesicles and the accessory glands being of distinct help in determining the 
ripeness or unripeness. 
