THE INTERNAL ANATOMY OF MOSQUITOES. 



Early investigators already did considerable work on the internal anatomy of 

 mosquitoes and since the discovery of their relation to disease there has been 

 much activity along this line. Already in 1851 Dufour, in his monumental 

 work on the anatomy of the Diptera, gave a very clear description of the digestive 

 and reproductive systems of mosquitoes, based largely on dissections of Culiseta 

 annulatus. In a work like the present which attempts to cover the greater part 

 of the field of our knowledge of mosquitoes, this important subject should not 

 be omitted, but time has not permitted us to make original studies of the internal 

 anatomy which has seemed to us to demand less attention than the other aspects. 

 Several papers bearing upon this subject might be mentioned, especially the 

 studies of Pressat and of JSTuttall and Shipley, the careful paper on the ali- 

 mentary canal of the mosquito by Millet P. Thompson, and others. In order 

 that this work shall not be published without some consideration of this topic, 

 the authors have asked the permission of Dr. J. W. W. Stephens, of the Liverpool 

 School of Tropical Medicine, to use the chapter on this subject from the excellent 

 work entitled " The Practical Study of Malaria and Other Blood Parasites," by 

 Stephens and Christophers, published by The University Press of Liverpool, 

 1908. Doctor Stephens has consented, and the following account of the anatomy 

 of a female Anopheles is taken from this work : 



GROSS ANATOMY. 



"T-HE ALIMENTARY CANAL. 



" The alimentary canal is specialized on account of the blood-sucking habits 

 of the mosquito. It differs from many insects in not possessing any csecal 

 diverticula of the mid-gut. It also differs in the possession of five malpighian 

 tubules, these being in insects usually even in number. 



" The parts of the alimentary canal are as follows : 



The mouth 



The pharynx with pumping organ 



The oesophagus 



The oesophageal diverticula 



The homologue of the proventriculus "I 



The stomach (so-called) [-The mid-gut. 



The pylorus 



The fore-gut. 



The pyloric dilatation 



The ileum 



The colon 



The rectum with rectal papillae 



The hind-gut. 



" The mouth, pharynx, and oesophagus are ectodermal in origin, and both the 

 mouth and pharynx are lined with chitin. The hind-gut is also ectodermal in 

 origin ; it does not possess, however, any portion lined with chitin. The mid-gut 

 is the true digestive portion of the tract. 



" TJie Pharynx. — The pharynx, which is lined throughout its extent with 

 chitin, passes upwards and backwards through the ganglionic ring formed by 



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