Arsenic not injurious to Larves of Flies. 167 
~ ever in a perfect state of preservation, being full of pup, just 
, before they were lost. The empty shells of other chrysalids, 
_ which had been formed at the same time as the above, were 
_ heyertheless found about the room from time to time within the 
_ Six weeks following their formation, indicating that some of 
_them had been metamorphosed, as the appearances of these 
shells were normal and no larve other than those which had 
_ fed upon the arsenicated specimens had been admitted to the 
_ apartment. 
without much success it must be confessed owing to the facility 
_ With which animal tissue is hardened by arsenious acid. If bits 
matter how dilute the solution may be—the arsenious acid will 
his hardening may indeed be somewhat delayed by vrappiag 
the flesh in moist cloths, in which ca 
covered with a strong solution of it; but these worms never at- 
tamed maturity in any of my experiments: they perished for 
Tn this case the grabs, an hour or two after leaving 
would commence crawling about very rapidly, evide 
irritated by the solution with which they were 
know how quickly flies themselves are 
; ar destroyed by 
et being the active ingredient of nearly all the popular 
