NO. 2 RECOGNITION AMONG INSECTS — McINDOO 4I 



they are perhaps similar in function to the caruncles described by 

 Laboulbene. 



Haase (1889a) says that the delicate chitin of these evaginated 

 sacs is covered with finely netted ridges and that secreting tubules 

 carry the secretion of the unicellular glands to the exterior through 

 fine pores. 



Klemensiewicz (1882) found oblong unicellular glands lying just 

 beneath the hypodermis of the caruncles in the same species that the 

 above two writers examined. The external end of each cell is attenu- 

 ated and passes through the hypodermis and chitin. An efiFerent canal 

 leads from the exterior opening and ends in the cell near the nucleus. 



At this place might be mentioned the function of the cornicles of 

 aphids. According to the latest researches, the aphids smear the 

 secretion from these tubules on their enemies ; the secretion thus 

 has a protective function and perhaps its odors are also repellent 

 (Wheeler, 1913, pp. 343-346). 



3. PALPI OF A TRICHOPTERON AS SCENT-PRODUCING ORGANS 



Miiller (1887) says that each male of Sericostoma personatum 

 that he held under his nose emitted a distinct odor resembling the 

 odor from vanilla, and he thinks that this odor came from the wide 

 maxillary palpi. Instead of the male palpus having four long joints 

 as found in that of the female, it has but one joint and this is ladle- 

 like with a flange on all sides. Inside the flange the surface of the 

 ladlelike joint is covered with a tuft of fine hair. When males and 

 females were kept together in a large vessel he noticed that a male 

 placed himself against a female whereby the tuft of hair unfolded. 

 He regards the hair and flange as a means for preventing a too rapid 

 evaporation of the odoriferous secretion which he imagines comes 

 from the interior of the joint, although he did not work out the 

 anatomy of this organ. 



4. GLANDS IN THORAX AS SCENT-PRODUCING ORGANS 

 (a) GLANDS IN PROTHORAX OF WALKING-STICKS 



Scudder (1876) says that both sexes of Anisomorpha buprestoides 

 are able to spurt a strong fluid or vapor from a pair of pores on 

 the thorax ; he considers this as a means of defense. Each pore lies at 

 the bottom of a large deep pit on either side of the upper anterior 

 surface of the prothorax. In Diapheromera the pores are smaller and 

 do not occupy a position along the dorsum in which they are found in 

 Anisomorpha and Autolyca. In Autolyca pallidicornis each of the 



