8(5 The Food Relations of the Carab'uhr and Coccinellida' . 



which could thus be acquired by patient study, was often quite 

 surprising. While it was of course rarely possible to distinguish 

 species, or even genera, all the fragments could usually be classi- 

 fied with some fair degree of definiteness; and tliere was com- 

 monly no difficidty in making satisfactory estimates of the ratios 

 of the diflferent food elements present. 



In some of the most important cases, the facts elicited were of 

 the highest degi'ee of exactness. Several collections of preda- 

 ceous beetles were made in situations where some particular 

 species of noxious insect was especially abundant, with a view to 

 determining to what extent the latter was preyed upon by its 

 supposed enemies. In such cases it was not difficult to tell with 

 certainty, even from very minute fragments, whether the given 

 insect had been eaten or not. Even where no solid structures 

 were present, and the contents of the alimentary canal were 

 entirely fluid, it was still usually possible to say whether these 

 fluids had an animal or a vegetable origin. After many observa- 

 tions and some experiments, it was found that partially digested 

 animal food in the stomach of a beetle was commonly bathed in a 

 black juice, which, when examined under a high power of the micro- 

 scope, was seen to contain nothing but a minutely divided flocculent 

 matter, probably composed of irregular aggregations of 

 fat droplets and other organic particles. This fluid was never 

 found in connection with purely vegetable contents, but some- 

 times filled the stomach alone, and contained nothing to indicate 

 its origin. In all the latter class of cases I have regarded it as 

 proof that the food had been derived from animal sources, proba- 

 bly usually consisting of the juices of insects recently captured. 



For the determinations of the fungi mentioned herein, I am 

 indebted chiefly to Prof. T. J. Burrill, of the Industrial University 

 at Champaign. 



The insects dissected for this paper were partly obtained in the 

 course of miscellaneous collecting, and partly secured for me 

 especially for the purpose, by one of my entomological assistants, 

 Mr. F. M. Webster, who kept careful notes of the situations in 

 which the specimens were taken, the hour of the day when they 

 were captured, and the objects upon which it seemed probable 

 that they had lately fed. Examples of the latter were also fre- 

 quently bottled with the specimens, for comparison. The special 



