PSYCHE 
Vol. 64 December, 1957 No. 4 
THE PRESENCE OF A PERITROPHIC MEMBRANE 
IN SOME AQUATIC HEMIPTERA 
By Margaret C. Parsons 1 
Harvard Biological Laboratories, Cambridge, Mass. 
Although the peritrophic membrane was formerly be- 
lieved to be absent in the order Hemiptera, Sutton (1951) 
has reported its presence in at least two species of Corixi- 
dae. It appears now that a peritrophic membrane is present 
in a second cryptocerate family, the Nepidae. 
In a recent study on the digestive system of water bugs, 
the author made serial sections through the midguts of 29 
adult specimens of Ranatra fusca P.B. Of these, four indi- 
viduals showed evidence of what might be interpreted as a 
peritrophic membrane. In two of the four, the membranous 
material was found throughout the midgut; one of these 
is shown in Figure 1. In a third, it was limited to the anter- 
ior dilated portion of the midgut, while in the fourth speci- 
men it was present only in the narrow posterior region of 
the mesenteron. 
The membrane appeared to be of the type which is se- 
creted by the midgut epithelium in general (the Type I of 
Wigglesworth, 1950) rather than by a limited group of 
cells. In most sections it seemed to be formed by the 
condensation, in the lumen of the gut, of a network of fine 
strands of cuticula, secreted by the midgut cells. In some 
areas, however, the membrane, which varied in width from 
one to approximately four micra, appeared to be delamin- 
ated directly from the surface of the epithelium. 
In the two individuals which showed this structure 
throughout the midgut, it was not a continuous membrane. 
1 This project was carried out partly during the tenure of a National 
Science Foundation Predoctoral Fellowship and partly under the Ellen 
C. Sabin Fellowship, awarded by the American Association of University 
Women. 
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