The Proventiriculus of a Hydropsyche 



Larva'"' 



ALICE AYR NOYES 



I. Introduction 



The proventriculus has been the object of much study in certain 

 famiHes of the Orthoptera (Locustidae, Gryllidae, Blattldae and 

 Mantidse), Coleoptera (Dytiscidae, Carabidae and Scolytidas), Hy- 

 menoptera (certain Vespidse and Formicidae), and Odonata, but 

 comparatively little is known of its structure in the Trichoptera. 



While making a study of the food of Hydropsychid larvae, my 

 attention was called to the remarkably well developed proventric- 

 ulus. The details of its structure show marked departures from 

 the ordinary type and will be discussed in detail later. I have 

 therefore undertaken a careful study of its structure in the larvae 

 of certain species of the genus Hydropsyche, and here shall con- 

 sider it under three heads, — general morphology, histology, and 

 physiology. 



This work was done under the direction of Professor William 

 A. Riley, to whom I wish to express my appreciation for his kindly 

 interest and helpful criticism. 



The results of this work have been based upon a study of the 

 organ by dissection, and by means of serial sections, both cross and 

 longitudinal. Examinations of the food-content of the proven- 

 triculus, as well as of the regions immediately preceding and fol- 

 lowing it, were made. 



In the material sectioned, the larvae were killed by decapitation, 

 whereupon the anterior part of the alimentary canal shot out and 

 was cut off and placed at once into the fixing fluid. Both Gilson's 

 fluid, and a saturated aqueous solution of corrosive sublimate + 5% 

 glacial acetic acid were used with good results. Some of the ma- 

 terial was stained in toto with borax carmine, and some on the slide 

 with Delafield's haematoxylin and eosin. Cedar oil was used as a 

 clearer, and all of the material was embedded in paraffin. The 



* Contribution from the Entomological Laboratory of Cornell University. 



