ANATOMY AND PHYSIOLOGY 



I2 7 



organs themselves. Thus a butterfly with male wings on the right side 

 and female wings on the left would have a testis on the right side of the 

 abdomen and an ovary on the left side. 



True hermaphroditism, existing "only when the essential organs of 



reproduction are united in one individual/' 

 and are functional, is said to occur "nor- 

 mally in a peculiar wingless termitophilous 

 fly, Termitoxinia. Other instances of her- 

 maphroditism among insects are, strictly 



FIG. 1 86. Types of ovarian 



tubes. A , without nutritive cells ; 

 B, with alternating nutritive and 

 egg-cells; C, with terminal nutri- 

 tive chamber, c, terminal chamber; 

 e, egg-cell; ep, follicle epithelium; 

 /, terminal filament; s, strands 

 connecting ova with nutritive 

 chamber; y, yolk, or nutritive 

 cells. Prom Lang's Lehrbuch. 



0' 



FIG. 187. Ovum of a butterfly, Vanessa, in its fol- 

 licle, e, follicle epithelium; g, germinal vesicle; n, 

 branching nucleus of nutritive cell; o, ovum. After 



WOODWORTH. 



speaking, examples of gynandromorphism, 

 in which secondary sexual characters of 

 both sexes occur in the same individual. 

 A gynandromorph often has ovaries and 

 testes at the same time, but both are no 

 functional. 



Parthenogenesis. Reproduction without fertilization is a normal 

 phenomenon in not a few insects. This parthenogenesis may easily be 

 observed in plant lice. In these insects there are many successive 

 broods consisting of females only, which bring forth living young; at 

 definite intervals, however, and usually in autumn, males appear also, 

 and fertilized eggs are laid which last over winter. This cyclic reproduc- 

 tion, by the way, is known as heterogeny. Among Hymenoptera, 

 parthenogenesis is prevalent, usually alternating with sexual reproduc- 

 tion, as in many Cynipidae. In some Cynipidae, however, males are 



