ANATOMY AND PHYSIOLOGY 143 
In each ovarian tube, or ovariole, are found ova in succes- 
sive stages of growth, the largest and oldest ovum being near- 
est the oviduct. In the primitive type of egg-tube, as in Thys- 
anura and Orthoptera (Fig. 183, 4) every chamber contains 
an ovum; in more specialized 
types, every other chamber con- 
tains a nutritive cell instead of a 
germ cell, the nutritive cells serv- 
ing as food for the adjacent ova 
(5); or the nutritive cells, in- 
stead of alternating with the ova, 
may be collected in a special 
chamber, beyond the ovarian 
chambers (C). An egg-tube is 
usually prolonged distally as a 
terminal filament, or suspensor, 
the free end of which is attached 
near the dorsal vessel. 
Ovaries and testes arise from 
indifferent cells, or primitive 
germ cells, which are at first 
exactly alike in the two sexes. 
In the female, certain of these 
cells form ova and others form a Types of ovarian tubes. A, with- 
‘ollicle a | Son nye: out nutritive cells; B, with alternat- 
Jo icle around each ovum ( 1g. ing nutritive and egg-cells; C, with 
184). In the male the primary terminal nutritive chamber; c, ter- 
4 ie : rf minal chamber; e, egg-cell; ep, fol- 
germ cells form cells termed licle epithelium; f, terminal fila- 
Sas ara a c a ment; s, strands connecting ova 
spermatogoma, each of these with nutritive chamber; y, yolk, or 
torms a Spermatocyte, and this nutritive, cells—From Lang’s Lehr- 
é . - buch. 
gives rise to tour spermatozoa. 
Hermaphroditism.—The phenomenon of hermaphrodi- 
tism, or the combination of male and female characters in the 
same individual, occurs only as an extremely rare abnormality 
among insects. Speyer estimated that in Lepidoptera only 
one individual in thirty thousand is hermaphroditic. Bertkau 
(1889) listed 335 hermaphroditic arthropods, of which 8 were 
