374 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Larval Stages op Pachysima ^thiops. 



(A) Second, (B) third, and (C) fourth (full-grown) larval stages of 

 Pachysima xthiops. 



The exudation is mainly blood-serum plus nutrient material con- 

 tributed by the fatty body. It probably escapes under pressure through 

 microscopic pores in the cuticle. There may also be exudation from 

 special skin-glands. This may evaporate from or be licked, off special 

 tufts of setaB. 



According to Wheeler, who confirms Rabaud's observations on some 

 tropical wasps, there is a relationship of nutritive exchange between 

 the larva3 of some' ants and the workers. For this the term "tro- 

 phallaxis " is proposed, and the theory suggested is that this inter- 

 relation lies at the basis of the social life of ants. In a widening vortex 

 it may pass from an exchange between larva and female to an exchange 

 between adults, or between ants and their guests, or between ants and 

 Aphides. The paper is one of extraordinary interest. J. A. T, 



Dimorphic Colouring- in Lepidoptera. — Arnold Pictet (6'. R. Soc. 

 Fhys. Hist. Nat. Geneve, 1918, 35, 17-22). The author has calculated 

 that 99-6 p.c. of insects are eliminated in early Hfe, hence the large 

 number of eggs usually laid by the female. Homochromic or protective 



