igoi] ENTOMOLOGICAL NEWS. 259 



Two series of six beetles each were put through each of these 

 seven experiments. Each beetle was weighed and measured, 

 the length being taken from the tip of mandibles to the tip of 

 abdomen, and the breadth at the middle of the wing-covers. 

 The first six beetles were allowed a rest of twenty-four or more 

 hours between each experiment, and their weights were taken 

 ever}' fourth day. The second six were more carefully weighed, 

 put through the experiments in quick succession and imme- 

 diately weighed again. The loss of weight was thus found, to 

 see if any constant relation existed between the weight lost and 

 the work done. Two beetles were kept as checks upon these 

 loss of weight experiments. 



In the first three experiments the device shown in Fig. 2 

 was used for measuring the strength of the beetles. A watch 

 spring was selected of such size that it could be used to meas- 

 ure any tension from one-tenth of a gram to over two hundred 

 grams, and straightened somewhat so as to form a single loop. 

 One end of the spring was securely clasped to a board by means 

 of a screw through a small washer ; the other end was bent 

 into a hook so as to hold the thread by which the beetle pulled. 

 A knot tied in the thread a short distance from the hook formed 

 a mark which could be easily followed with the eye, and by 

 placing a millimeter scale in line with the spring and beyond 

 the knot in the thread an easy means was obtained of accu- 

 rately measuring the elongation of the spring when subjected 

 to a pull. The thread from the spring was passed forward 

 below the body of the beetle between the middle and hind 

 legs and tied around the pro-mesothoracic constriction. The 

 beetles appeared very willing to exhibit their strength, and as 

 soon as they found themselves attached they would endeavor 

 to escape, showing a decided tendency to travel straight toward 

 the window. 



During the pull more strain seemed to be exerted upon the 

 apical tibial spurs, which are well developed upon all the legs, 

 than upon the tarsal claws, of which only the fore pair appeared 

 to be of any considerable assistance. It was found that the 

 rough surface of the wood (as the beetles had left it upon the 

 excavation of their burrows) afforded so much more iavorable 



