042 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the mid-gut, the primordium of which arises from the anterior and 

 posterior ends of the germ-hand. The median part, the mesodermic 

 groove, grows forwards and hackwards, forcing the anterior and posterior 

 regions inwards, where they form the beginning of the endoderm ; but 

 mesoderm and endoderm are in origin separate structures, the relations 

 between them described by other authors being produced secondarily 

 by differential growth. 



Sense-organs in Collembola.* — Karl Absolon, in the course of an 

 account of new Collembola from Moravian caves, discusses various 

 forms of antennal sense-organs. In Tetrodoniophora gigas, the organ 

 of the third antennal segment reaches its fullest development. It con- 

 sists of seven outer and seven inner club-shaped projections, each being 

 supplied by a fibre of the antennal nerve, and each protected by a 

 bristle. In Achorutcs and other genera, the third and fourth segments 

 of the antenna? bear numerous thickened projections, apparently of 

 olfactory nature, which are in origin modified bristles. In Neanura 

 there is a very complicated organ on the fourth segment, consisting of 

 three rounded projections, in the vicinity of which are sensory hairs, as 

 well as olfactory clubs. In Podura aquatiea, a similar organ occurs, 

 but with only one sensory bristle and no olfactory clubs. 



Determination of Sex in Silkmoth.t — C. Flammarion began in 

 1894, at the Observatory of Juvisy, a series of observations on the in- 

 fluence of different colours on plants and animals, and he communicates 

 an account of some experiments with silkworms. His results lead him 

 to think that the production of male moths is favoured most by coloured 

 rays and by restricted food (or appetite). 



Mosquitoes.* — Dr. L. 0. Howard has published a useful volume of 

 studies on mosquitoes; — he tells how they live, how they carry disease, 

 how they are classified, and how they may be destroyed. 



Fire-fly's Light the Cheapest Form of Light.§— S. P. Langley and 

 F. W. Very show, by their study of the radiation of the fire-fly (Pi/ro- 

 phorus noctilucus), that it is possible to produce light without heat other 

 than that in the light itself, and that this is actually effected in the fire- 

 fly in a manner much more economical than any human devices for 

 light-production. " Nature produces this cheapest light at about one- 

 i'our-hundredth part of the cost of the energy which is expended in the 

 candle-flame, and at but an insignificant fraction of the cost of the 

 electric flame or the most economical light which has yet been devised. 

 . . . There seems to be no reason why we are forbidden to hope that 

 we may yet discover a method (since such a one exists and is in use on 

 the small scale) of obtaining an enormously greater result than we now 

 do from our present ordinary means for producing light." 



Supernumerary Wings in Pieris rapae.|| — G. W. Tannreuther de- 

 scribes this rare occurrence in a prepupa. The abnormal structure 



* Zool. Anzcig., xxiv. (1001) pp. 575-85 (8 figs.), 

 t Comptes Remlus, exxxiii. (1901) |.p. 397-400. 



j Mosquitoes, by L. O. Howard, New York, 1901, xv. and 241 pp., 1 pi., ami 

 50 figs. § Smithsonian Misc. Collections, 1258 (1901) pp. 1-20 (3 pis ) 



U Zool. Anzeig., xxiv. (1901) pp. 620-2 (3 figs.). 



