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 Nuttall 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that this work shall not be published without some consideration of this topic, 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. 
“THE 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 cecal 
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 fm e fore-gut. 
The csophagus 
The esophageal diverticula 
The homologue of the proventriculus 
The stomach (so-called) The mid-gut. 
The pylorus 
The pyloric dilatation 
The ileum Sig 
The colon frm hind-gut. 
The rectum with rectal papille 
“The mouth, pharynx, and cesophagus 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. ; 
“The Pharynz.—The pharynx, which is lined throughout its extent with 
chitin, passes upwards and backwards through the ganglionic ring formed by 
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