370 KANSAS UNIVERSITY SCIENCE BULLETIN. 



Mr. Emery in his paper on the "Morphology and Biology of 

 Simulmm vittatmn" gives some interesting data regarding the 

 biology of this insect, to which the reader is referred. 



TECHNIQUE FOR THE STUDY OF GROSS ANATOMY. 



Most of the studies of the gross anatomy of the Simulium 

 fly were made by means of free dissections under the binocu- 

 lar.* Quite a number of the body tissues of the fly are trans- 

 parent, and for a study of these the direct sunlight gave the 

 best illumination. A spot light made by focusing sunlight 

 through a reading glass gave excellent illumination. These 

 studies were verified by serial microtome sections. 



The comparatively small size of the fly (3 mm.) necessitated 

 the use of a technique somewhat more delicate than is usually 

 necessary, and inasmuch as the majority of students of small 

 forms have failed to record their methods of study, I have 

 felt it desirable to give a brief account of the technique used 

 in these studies. 



The needles used in the dissection work were made by 

 placing the base of minuten nadeln points (used in mounting 

 small insects) in handles of wood and grinding the points on 

 emery paper until they were small enough for use. 



The flies were held in any given position by paraffin. To 

 do this, some paraffin was placed in a small shallow porcelain 

 staining dish, and warmed to melting point. The fly was then 

 placed about half its width in the paraffin in the desired posi- 

 tion and the paraflSn cooled. 



The dish was then filled with either normal salt solution or 

 with 50 per cent alcohol, depending upon whether the material 

 was fresh or fixed. With careful work and a steady hand one 

 could determine the various systems with considerable ac- 

 curacy. One fly would usually serve for several days' dissection 

 study, and by covering the dish with a lid and inverting a 

 tumbler over all to prevent evaporation of the alcohol the 

 specimen would be ready for further study without the usual 

 delay. 



Most of the dissections were made with the fly on its side. 

 The large muscles of the thorax and the deep incision of the 

 exoskeleton between the thorax and the abdomen made dorsal 

 dissections quite unsatisfactory. Ventral dissections were 



* I used a Zeiss machine and found that the No. 2 nnd No. 4 eye pieces used with tlie 

 A2 objective gave by far the most satisfactory results for the study of general anatomy. 



