720 SUMMARY OF CURRENT RESEARCHES RELATING TO 



togaster scutellaris, Lasius emarginatus, and L. fuliginosus, form a series 

 in both these respects. 



Connection between Mid-Gut and Hind-Gut in Larval Hymen- 

 optera.* — C. Rengel has investigated this point in the larva3 of Vespa 

 germanica, Apis mellifica, and Lasius niger. He finds that at the 

 boundary of the two regions the embryonic condition persists through- 

 out the whole of the larval period unchanged {Apis, Lasius), or almost 

 unchanged (Vespa). The mid-gut is, from the start, in organic con- 

 nection with the hind-gut. The muscularis layer, the membrana 

 propria, and the epithelium, pass from the one region to the other 

 without interruption. The expulsion of the stored contents of the 

 mid-gut is not occasioned by any new formation, but is wholly due to 

 the expansion of the narrow region. 



Interesting Case of Parasitism.f — K. Griinberg recalls the remark- 

 able parasitism of the ant-decapitating fly, described some years ago by 

 Theodor Pergande.+ An ant, Camponotns pennsylvanicus Greer, which 

 lives in hollow trees and stumps, is attacked by a fly, Apocephalus 

 pergandei Coqu., which lays its eggs on its victim's body. The larvse 

 hatch and penetrate to the head, killing the ant after decapitating it. 



Beetle Embedded in Wall of Human Intestine.§ — D. Sharp re- 

 cords a case observed by W. H. Ligertwood. The lower part of the ileum 

 of an old man of 73 showed two small oval, blackish lumps ; the upper 

 one, about eighteen inches above the ileo-cgecal valve, contained a living 

 weevil {Otiorhynchus tenebriosus) about half-an-inch long. It lay 

 between the mucous membrane and the other coats of the intestine ; 

 there were no signs of a cyst-wall, nor of any opening. Dr. Sharp 

 corroborates the identification of the beetle, and calls attention to recent 

 experiments by Thebault, which show that the larva of Piophila 

 casei — the common cheese-maggot — can traverse the whole length of 

 the human alimentary canal without being killed. It appears, there- 

 fore, that accounts of the finding of living insects in the human 

 alimentary canal must not be rejected on account of the inherent 

 improbability of life being maintained in such a situation. 



Coloration of Coleoptera.|| — "W. L. Tower shows that the most 

 important of insect colours are those of the cuticle. They are not due 

 to drying, oxidation, secretion, or like processes, but are produced by 

 katalytic agents working in the cuticle. The colours develop as the 

 cuticula hardens, and appears first, as a rule, upon sclerites to which 

 muscles are attached. The pigment develops from before backward, 

 and, approximately, by segments, excepting that it may appear upon the 

 head and most posterior segments simultaneously. 



A study of the cuticle revealed the existence of enzymes of a new 

 class, called chitases. They operate in the hardening and pigmenting of 

 the cuticle. An outer or primary cuticula of chitin is distinguished 

 from an inner layer, composed of a carbohydrate allied to tunicin. The 



* Zeitschr. Wiss. Zool., lxxv. (1903) pp. 221-32 (2 pis.). 



t Biol. Centralbl. xxiii. (1903) pp. G79-80. 



X Proc. Entona. Soc. Washington, iv. No. 4, p. 497, 1901. 



§ Proc. Cambridge Phil. Soc, xii. (1903) pp. 199-200. 



|| Decennial Publications, Univ. Chicago, x. p. 40 (3 pis.). 



