300 COMPAEATIVE ANATOMY. 



of separate orifices, and resemble the Araclinida in forming an annular 

 portion. 



Steix, F.j De Myriapodum part, genital. Berol. 1811. 



§ 233. 



Notwithstanding the s'reat variations of more subordinate cha- 

 racters, the generative organs of the Insecta present on the whole 

 a well-marked uniformity of structure. The organs and their 

 accessory parts almost always lie in the abdomen, and generally 

 open below, or in front of, the anus. The eighth abdominal 

 segment generally seems to carry the genital orifice. In the 

 Strepsiptera only is the female generative orifice placed some 

 way forwards. The germinal glands are, as a rule, disposed 

 in pairs, and retain this condition, although there are indications 

 of the primitively single arrangement, or of a connection between 

 the germ-glands of either side, as in the Araclinida and Myria- 

 poda. Each germ-gland is composed of a varying number of 

 equal parts, which are generally tubular in form, grouped into 

 tufts, and united at an efferent duct. The ducts of the two germ- 

 glands seldom have separate orifices. They are almost always 

 united for a certain distance, and receive, before they unite, acces- 

 sory organs, formed by the differentiation of a portion of their 

 walls. In the females these organs appended to the ducts are 

 sometimes pouch-like, or vesicular portions, which either serve for 

 the reception of the male copulatory organ (bursa copulatrix), or 

 as glandular organs of various kinds (cement glands), and also as a 

 store-house for the sperm (receptaculum seminis). In the male, the 

 paired-glands of the efferent ducts are greatly developed. In 

 addition to them there are other parts which function as seminal 

 vesicles (vesiculoa seminales). 



External organs, which are generally formed by the metamor- 

 phosis of the terminal metameres and their appendages, are con- 

 nected with the end of the genital duct ; in the males these form 

 copulatory organs, and in the female vary in form (as ovipositors). 



§ 234 



In the female apparatus the complex of ovarian tubes, which is 

 generally regarded as an " ovary," undergoes the most considerable 

 modifications. 



The relations which these tubes have to the formation of ova is 

 somewhat different to those which they have in other Arthropoda. 

 Each separate ovarian tribe (Fig. 158) gradually widens at one end, 

 where it is inserted into the oviduct; the opposite end is generally 

 slender, and is often, indeed, continued into a fine filamentous process. 

 When there are a large number of ovarian tubes, the free ends are 

 directed towards a centre and connected together. The ova are 



