202 Annals Entomological Society of America [Vol. IX, 



femoro-tibial articulations when only slightly irritated, but 

 after they have been handled and kept in captivity for a short 

 time a stronger mechanical stimulus is necessary to cause them 

 to force liquid from the articulations. Beetles kept in confine- 

 ment four months with plenty of pumkpin leaves and water 

 were tested to ascertain how many drops of liquid a leg is able 

 to expel in rapid succession. A hind leg was able to eject as 

 many as six small drops with only a few seconds intervening 

 between the emission of any two of them. A middle or front 

 leg was not able to eject quite so many drops. Under a low- 

 power lens the liquid seemed to come from the articular mem- 

 brane and from the extreme proximal end of the tibia. Each 

 time the leg was irritated a much smaller drop was also seen on 

 the first tarsal joint. 



To determine the strength of the mechanical stimulus 

 required and the mechanics employed in ejecting the liquid to 

 the exterior, beetles were placed on their backs under a low- 

 power lens. When the distal end of a femur was gently touched 

 w4th a needle, a muscular contraction instantly folded the tibia 

 against the femur, and a small drop of liquid appeared simul- 

 taneously at the articulation. The drop always increased 

 slightly in size after first appearing. A stronger stimulus with 

 the needle was required to bring about the emission of each 

 succeeding drop. The sixth drop, the smallest of all, w^as 

 produced only by rubbing the entire femur hard with the 

 needle. Legs with the tibiae folded against the femur can also 

 eject the liquid, but not so easily. Muscular contractions may 

 be noticed in them. Legs held out straight are also able to 

 eject the liquid, but with much difficulty, and muscular con- 

 tractions are very evident. 



The liquid ejected has an amber color and a very ofi'ensive 

 odor. It is almost as bitter as quinine and when tasted, a bitter 

 taste lingers in the mouth for almost a half day. It is slightly 

 viscid and dissolves slowly in water. In order to compare it 

 with blood entirely free of any hypodermal glandular secretion, 

 the wings of the same live beetles were cut in two. It will later 

 be shown that the wings do not contain any hypodermal glands, 

 but they are full of blood. Blood from the wings has the same 

 color, the same taste and probably the same odor as the ejected 

 liquid, but the blood is not viscid and it dissolves readily in 

 water and does not sink as quickly as the ejected fluid. 



