— 26 — 



orientalis, if only the establishment of such a liomology were 

 not prevented, owing to the different orientation of the glands in 

 Phyviateus on the dorsal side of the fold (between the I and II 

 abdominal segments), and in Periplaneta on the ventral side 

 (of an analogous fold between the V and \l segments). 



In solving the cause of the discharge of the foamy fluid 

 in Phymateus it is necessary to base the statements on the 

 fact that the greatest discharge takes place out of tlie fold bet- 

 ween the first and second segments of the abdomen, into which 

 the aforesaid sac-shaped gland opens. I presume that this is 

 the gland that emits the foamy fluid covering the body of 

 the insect, when taken into the hands. It is impossible to 

 decide as to the participation of the blood in forming the 

 foam, as in none of the hollow tendons (which open into the 

 same dilatation of the fold between the first two segments, as 

 the sac-shaped gland) are any openings which could have 

 served for discharging the blood to the exterior to be seen. 

 Even if the latter process be allowed for, the foamy secretion 

 would have to be considered, at any rate, as a mixture of 

 blood and the secretion of the sac-shaped gland. 



The dermal glands which are in my opinion homodina- 

 mous to the paired odoriferous glands of Periplaneta orientalis 

 may hardly be supposed to play any role in the formation of the 

 foamy fluid, owing to their too insignificant size and topo- 

 graphical position in the body of the insect. 



The presence of a graiuilous secretion in the hollow ten- 

 dons of the hind legs and in other recesses and slits of the 

 body I explain by the foamy secretion of the sac-shaped 

 glands getting into them when it flows over the body. This 

 secretion is probably very viscous; on account of that, when 

 slowly pressed out, the liquid forms bubbles in mixing with 

 air and produces a foam covering the body of the insect. 



The discharge of the foamy secretion in Phijmateus is to 

 be considered as a protective reaction, and in causal depen- 

 dence with it is to be put the very slight tendency and 

 possibly the complete absence of a capability for autotomy 

 of the hind legs, the slow movements of Phijmateus, and the 

 presence of many defective individuals in nature which are 

 supposed to have been attacked by insectivorous animals and 

 to have escaped danger with only slight injury for themselves. 

 Explanation of figures. 



