REPRODUCTIVE ORGANS 79 



" When the reservoir-stomach, which is supplied with longitudinal and en- 

 circling muscles that furthermore are assisted by the pressure of the body, has 

 little by little given up the nourishing liquid to the mid-gut air again takes its 

 place, 



" The air is in part swallowed, as one can observe in emerging * mosquitoes 

 by the increasing inflation of the abdomen and the movements of the pharynx- 

 pump, very nicely visible through the as yet unpigmented clypeus. Later, how- 

 ever, it is also produced in situ, in the form of carbonic acid, through vegetable 

 comensals, an yeast mould (Laveran, Schaudinn) ; at the same time an enzyme is 

 formed in which Schaudinn has recognized the poisonous, wheal-producing 

 substance which the mosquito introduces when stinging." 



"THE REPRODUCTIVE SYSTEM. 



" The organs of the reproductive system are : 



1. Ovaries. 



2. Oviducts and common oviduct. 



3. Mucus gland and duct. 



4. Spermathecffi and ducts. 



" The ovaries occupy a variable position dependent upon the state of their de- 

 velopment. In the newly-hatched mosquito they are small bodies lying in the 

 fourth and fifth abdominal segments close by the posterior portion of the mid- 

 gut, hind gut, and malpighian tubes towards the venter, so that eventually the 

 ovaries occupy nearly the whole of the posterior portion of the abdomen. Each 

 ovary consists of very many follicular tubes, each containing egg follicles in dif- 

 ferent stages of development. In the mature ovary the lower follicles have in 

 every tube become the large completely-formed egg. 



" The oviducts are muscular tubes passing from the ovaries. They join be- 

 neath the rectum to form the common oviduct, which is still more abundantly 

 supplied with muscle fibres, and which eventually opens beneath the anus. 



" The spermatheca is a chitinous sac, which in the impregnated female is filled 

 with a mass of spermatozoa. Its duct is long and twisted and opens into the 

 common oviduct near its termination. (In Culex spp. there are three sper- 

 mathecae.) 



" The mucus gland, globular or ovoid in shape, opens by a short duct into the 

 same region." 



Neveu-Lemaire has shown that the number of spermathecae or receptacula 

 seminis present in the female differs in certain genera. He determined that in 

 Anopheles there is but a single receptaculum seminis, in the oriental Manso- 

 niodcs uniformis there are two receptacula seminis and in Culex pipiens there 

 are three of these receptacles. We have found that in Uranotcenia and Aedeomyia 

 there is, as in Anopheles, but a single receptaculum seminis. In all the other 

 American mosquitoes we have examined, including several species of Mansonia, 

 there are three receptacula seminis. When three receptacula are present one of 

 them is often larger or smaller than the other two. 



"THE FAT-BODY. 



" The adipose tissue is disposed in two ways. 



" 1. As a general lining to the body wall, being nearly everywhere present 

 directly beneath the cuticle, and 



" 2. As lobular masses lying in among the organs and muscles. Thus a large 

 pad lies over the compound thoracic ganglion, and sends processes which lie in 



* " During the pupal stage the diverticula contain no air whatever, in the newly emerged 

 imago they are on the contrary dilated with air. The newly issued mosquito therefore floats 

 even on alcohol." 



