igoi] ENTOMOLOGICAL NEWS. 26l 



denc}' which the beetles showed to Hft by their heads, obsta- 

 cles under which they desired to crawl. In each experiment 

 the beetles were suspended horizontally from the clamp upon 

 a ring-stand by the tip of the abdomen and the pro-mesotho- 

 racic constriction (Fig. 5). In experiment 6 they were not 

 allowed to touch anything with their legs. The platform upon 

 which the weights were placed was suspended directly from the 

 head, the thread being fasted around the head just behind the 

 eyes and the horn, the height of the beetle being adjusted by 

 the clamp, so that w^hen the head was lowered the platform 

 w^ould rest upon the base of the stand. Weights were then 

 added as long as the beetle was able to lift the platform clear 

 of the stand. In this way, by the pro-mesothoracic muscles 

 alone, the weight lifted averaged 36.83 grams (35.41:1). 



The 7th experiment was performed under the same condi- 

 tions as the 6th, except that an opportunity was given the bee- 

 tles to use their forelegs by bracing them upon a piece of cork 

 adjusted to the correct height by another clamp upon the ring- 

 stand. This additional condition increased their lifting power 

 to an average of 127.5 grams (122.79:1). This experiment 

 shows great power in the forelegs. 



A single trial was made with one beetle to get an idea 

 of what the strength exerted in pulling would mean if 

 measured in the usual way as drawing a load. The " cart " 

 consisted of a pane of glass moving freely upon four ^-inch 

 steel balls placed on top of the table. The beetle, pulling 

 upon a cork surface as in experiment i , was harnessed to the 

 glass loaded with weights. The table top was not perfectly 

 horizontal, as was shown by the "cart" moving more easily in 

 one direction than in the other, but this inclination was not 

 sufficient to continue the motion of the load after it was started 

 down it. The beetle was, however, made to pull its load up 

 this slight inclination, and thus, with the conditions rather 

 against it, the beetle succeeded in pulling the apparently enor- 

 mous load of 1250 grams (11 16:1). When given the additional 

 advantage of pulling under the more natural conditions of its 

 burrow, the same beetle easily pulled a load of 3214 grams 

 (2870:1). While the last figures are astonishing, they give a 



