8 THE AMERICAN MONTHLY [Jan. 



my work is done in the evening, so that the intervals be- 

 tween the operations, described below, are often due to 

 such interruptions rather than to their being necessarily 

 required by the process. I do not think, however, that 

 anything would be gained, in the present instance, by 

 shortening any of the intervals given below. 



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

 piece 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 

 lamp by which the water was heated, being withdrawn 

 the moment the insect entered the water; this was done 

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

 being the only successful reagent for this purpose, ex- 

 cepting in cases where 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 with sufficient rapidity to 

 fix the enclosed protoplasm before post-mortem changes 

 have begun. The moment the fly, which was a female, 

 entered the water the proboscis 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 

 placed upon a small piece of glass (about one half of a 

 mounting slip) and the legs, wings, etc., were arranged 

 so as to afford the best display, another piece of glass of 

 the same size and shape as the first was placed over it, 

 but prevented from pressing upon the specimen, more 

 than just enough to hold it in place, by bits of glass, of 

 the proper thickness, being inserted between the ends of 

 the two plates; 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 between each change, to 40 p.c. — 

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



