INSECTS 121 



the testes consist of many fine spermatic tubules, in the walls of 

 which the sperm develop from the localized germ cells. Con- 

 nected with each testis and, in fact, with each spermatic tubule, 

 is a larger conducting tubule, the vas deferens, which runs pos- 

 teriorly and enlarges to form a seminal vesicle in which the ripe 

 sperm, passed from the spermatic tubules, may be temporarily 

 stored. Near the posterior end of the abdomen, the right and left 

 seminal vesicles unite in the formation of a common duct which 

 opens to the exterior through the copulatory organ by which the 

 sperm are transferred to the female. 



Female Reproductive Organs. The eggs are produced in a 

 pair of ovaries which are situated in the same relative position in 

 the female as are the testes in the male. Also the general plan of 

 structure of ovary and testis is essentially the same. Thus the 

 ovary consists chiefly of a compact group of ovarian tubules in 

 which the eggs develop. Leading from each ovary is an oviduct. 

 The right and left oviducts, continuing posteriorly and ventrally 

 from the ovaries, unite in the midline, near the ventral body wall, 

 to form the vagina. This opens to the exterior through the 

 highly specialized egg-laying apparatus, the ovipositor. Open- 

 ing into the vagina is the seminal receptacle, in which the 

 male sperm are received, and also a glandular secreting organ, the 



BURSA COPULATRIX. 



Functional. Eggs formed in the ovary pass down the oviducts 

 and into the vagina. Here they are fertilized by sperm previously 

 received from the male and stored in the seminal receptacle. Two 

 membranes are secreted around each fertilized egg, and it is then 

 ready to pass from the female. The female Grasshopper lays the 

 fertilized eggs in a hole in the ground. This she drills very readily 

 by means of the beautifully adapted ovipositor mentioned above. 

 The number of eggs deposited at one time varies, but there may 

 be as many as 35. The fertilized eggs placed in the ground in the 

 fall remain there undergoing development until the following 

 spring when well-formed, but immature Grasshoppers hatch from 

 the eggs and force their way to the surface, where in a short time 

 they become active feeding individuals. 



Metamorphosis. Insects, with the exception of a few primitive 

 species, pass through a series of three or four life stages during 

 their development. This is known as metamorphosis. The 

 higher types of Insects, as we shall see later in the Bee, have four 



