210 Annals Entomological Society of America [Vol. IX, 



HOW REFLEX " BLEEDING " IS ACCOMPLISHED. 



The lumen in the extreme proximal end of the tibia is 

 divided into two almost equal chambers (Fig. 20, bs) by a mem- 

 brane ihx) extending across the leg. In structure and general 

 appearance this membrane resembles the hypodermis with 

 which it unites on each side of the leg. In that chamber con- 

 taining the nerve (w) and trachea (/r) lie only a few scattered 

 gland cells and only a small amount of blood may be seen in it. 

 The other chamber is full of blood and it is the one that con- 

 tains all the gland cells {glc) belonging to the two groups of 

 pores found on the tibia. No muscles are seen in the tibia at 

 this place. 



The lumen in the extreme distal end of the femur is likewise 

 divided into two chambers by a membrane. In sections passing 

 through the articulation, may be seen muscle fibers (Fig. 21, m) 

 at the extreme distal end of the femur, tracheal branches {tr) 

 running to the gland cells {glc), and a nerve (w) running through 

 the center of the articulation. All the space not filled by the 

 preceding structures may be called blood sinuses {bs). 



Under ordinary conditions in the natural environments of 

 the beetles all the reservoirs, conducting tubes and ampullae are 

 possibly kept constantly full of the glandular secretion. It is 

 reasonable to think that all parts of the cytoplasm of the gland 

 cells are slowly and constantly producing a secretion that flows 

 into the ampullae from which it gradually passes through the 

 conducting tubes to the reservoirs, if present, from whence it 

 passes through the efferent tubes to the exterior. On the sur- 

 face of the chitin the secretion forms a small circular film 

 around the exit of each pore. Since this secretion is quite 

 volatile and has an offensive odor, perhaps no further discharge 

 of the secretion is necessary to guard off most of the enemies of 

 this insect. During the constant discharge of this secretion no 

 reflex is called into play. 



. Since a pore lies near the base of each hair, and as many of 

 these hairs are innervated, a correlation between each tactile 

 hair and the pore near it might at once be suspected. To 

 imagine that the pore lies near the hair for mere protection is 

 not sufficient correlation, because the innervation of the hair 

 would not be needed, if only the protection of the pore is con- 

 sidered. A little speculation, therefore, may not be out of 



