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TEXT-BOOK OF ENTOMOLOGY 



2. The larval type, with two testes, whose four follicles are enclosed by a 

 common scrotal membrane (Bomlyx mori, Gastropacha quercifolia, Ichthyura 

 anachoreta and anastomosis, Saturnia p;/>'i, Aylia tau). 



3. The pupal type (since it first occurs in the pupa state), with a single testis, 

 which possesses an external median lace-like covering. (Adela, Lycsena.) 



4. The imaginal type, with a single testis enveloped by a lace-like scrotum, 

 within which the follicles are wound around the longitudinal axis of the testis. 

 (Most Lepidoptera.) 



In Neinatois there are twenty seminal follicles, the number of ovarian tubes 

 being the same. (Cholodkowsky.) 



In many insects the testes are not composed of tubes (follicles), but of button- 

 like bodies, each of which has its own duct. 



The color of the testes is usually white, but they may be orange (Decticus), 

 yellowish green (Locusta viridissima), or deep yellow (Chrysopa). 



The testes of Asilid flies are enveloped by a common dark-red membrane 

 rich in tracheae, like that in Lepidoptera which clothes the separate testicular 

 follicles. The two testes of Calliphora are enveloped by an orange-yellow cap- 

 sule, outside of which is a special membrane formed by the fat-body. (Cholod- 

 kowsky.) 



In the honey-bee the testis has two envelopes, the outer of which is formed 

 by the fat-body, the inner coat of connective tissue. The entire testis corre- 

 sponds to a portion only of that of Bombyx mori. 



The seminal ducts. - - The vasa deferentia are fine tubes, which vary 

 much in length; being short in many beetles and locusts, very short 

 in many Diptera (Syrphidae, etc.), very long in Cicada and many 

 beetles ; according to Burmeister, being in Dyticus 

 about five times, in Necrophorus and Blaps eight to 

 ten times, in Cicada 14 times, in Cetonia aurata 30 

 times, as long as the body. They either resemble 



a skein of silk, or form a 



tangled mass. 



The distal or lower 



end of the vasa is in 



many insects dilated 



into a sac or seminal 



- , , . , ,. FIG. 469. Male or- 



Fio. 468. Male organs of a vesicle, which serves lOf gans of Tomicus. Let- 



weevil, Iltilobiu* abieti* : If, testis ; ,r ,-rkfirm anrl ufnv tering same as in Fig. 



ftL, viis IU.f-e.-eMs; />, slime gland; the reception ailCl StOl- 468. - This and Fig. 



A7>', seminal vesicle; uSG, ejacula- f f i ^p^^l fl,,;,! S fr , om Judeich and 



tory duct. Nitsche. 



after it passes through 



the vasa deferentia. In the honey-bee the vas deferens is given off 

 from the reservoir, forms loops in and outside of the testis, and 

 passes to the seminal vesicle. The canal into which the vesicle 

 narrows does not open into the ductus ejaculatorius, but into the 

 glandulse mucosse; its epithelial cells are much vacuolated, and 

 have, therefore, a spongy appearance. (Koschewnikoff.) 



