LIBRARY

THE ANATOMY OF INSECTS 41
the APTERA (Iapyx), ISOPTERA,ORTHOPTERA, ODONATA,
and SIPHONAPTERA.
(2) Polytrophic - in which the nutritive or yolk cells alternate with the
oi)cytes. They may be grouped in chambers separated alternately by
constrictions in some NEUROPTERA, COLEOPTERA (Adephagous),
and HYMENOPTERA, or they may Occur alternately without
such dividing constrictions, as in LEPIDOPTERA and DIPTERA.
(3) Telotrophic or acrotrophic - in which the nutritive cells are crowded at
the upper apices of the ovarioles, as in HEMIPTERA and COLEOP­
TERA (Phytophagous), or combine to supply nourishment to each
oocyte by means of fine
protoplasmic tubules from
the nutritive chamber to
the ova.
The zones or regions recognizable in
the ovarioles are as follows:
(1) Terminal filament - the filamentous
apical prolongation
of the ovadole wall.
All the filaments of the
ovarioles in the ovary combine
into a single thread
and those of both ovaries
sometimes unite into the lateral muscle of
common median ovarian bursa copulotrix'
ligament which aids in sup- basal sheath of
ovlpositor--porting
the ovaries in the
body cavity. The ovarian
ligament is not present in
all insects. distal sheath of
(2) Germarium - the apex of the ovipositor--ovariole
below the filamentaceous
prolongation which
consists of a mass of cells
from which the primordial
germ cells and, in many insects,
also the nutritive cells
are differentiated.
(3) V itellarium - the major por·
tion of the ovariole which
encloses the developing
oviduct
'"N'''M''' gland
FIG. 22. The female reproductive system of
the apple maggot fly. Rhago/elis pomonellq
(Walsh), (After Dean, 1933.)
oOcytes and the nutritive epithelial layer of the wall invaginates
so as to surround each in a definite chamber or follicle. The cells
of the latter secrete the chorion of the ova and may also nourish the
oocytes. Ovarioles. except as primitive follicles, are wanting in the