8 THE AMERICAN MONTHLY f.Tan. 



my work is done in tlu' evening, so that tiie intervals be- 

 tween the oiKMatioiis, described below, are often diu' to 

 such interrnptiouH rather than to their being necessarily 

 required by the ]irocess. I do not think, however, that 

 anything would l>e gained, in the present instance, by 

 shortening any of tlie iiit<M-vals given below. 



The fly was placed under a boll-glass, together with a 

 j)iece of blotting paper which had been saturated with 

 chloroform, and the moment the insect ceased to move, 

 it was dropped into a small beaker of boiling water, the 

 lamj) by which the water was heated, being withdrawn 

 the moment the insect entered the water; this was done 

 for the purpose of killing and rixing the soft tissues, heat 

 being the only successful reagent for this purpose, ex- 

 cepting in cases wiiere the chitinous integument can be 

 slit up so as to allow the entrance of a liquid fixing 

 agent, no fixing agent excepting heat being known which 

 will penetrate through chitin witii sufficient rapidity to 

 tix the enclosed protoplasm before }»ost-mortem changes 

 have begun. The moment tlit> tly, whicli was a female, 

 entered the water the })roboscis aud the ovipositor were 

 fully protruded and extended, and remained so during 

 the succeeding manipulations. 



The insect was left in the hot water for about five 

 minutes and was thoroughly washed in it. It was then 

 j>laced upon a small piece of glass (about one half of a 

 mounting slij)) and the legs, wings, etc., were arrangeti 

 so us to alford the ])est dis[)hiy, another piet-e of glass of 

 the same size and shaj)e as the first was placed over it, 

 but prevented from pressing upon the specimen, more 

 than just enough to hold it in [)lace. by bits of glass, of 

 the {>roper thickness, being inserted between the ends of 

 the two [)lates; the whole was then bound together by 

 means of thread wound around them and dropped into a 

 jar of 30 p. c. alcohol which was changed, with intervals 

 of twenty-four hours lietween each change, to 40 p.c — 

 50 p.c. — 70 p.c. — 80 }).c. and 95 p.c. strength. 



