304 SUMMARY OF CURRENT RESEARCHES RELATING TO 



response to gravity, though they have httle effect on the reaction tc> 

 light. In a mutant stock called tan there is evidence of a sex-linkecJ 

 inheritance of indifference to light, which is apparently not due to any 

 structural defect. The diverse effectiveness of different coloured lights- 

 is defined. J. A. T. 



Digestion in Cockroach. — Eldon W. Sanford {Journ. Exper, 

 ZooL, VMS, 25, 355-412, 21 figs.) finds that the crop is the principal 

 digestive area. Its enzyme splits up fats, and three times as actively as. 

 the stomach. The crop is also the chief area for the absorption of fats, 

 and all the cells of its epithelium may share in absorbing. The crop is. 

 also an important storing organ ; it can store enough for two months. 

 The gizzard has an important sphincter action, and may keep back food 

 from the stomach for several days. The needles on the cushions are 

 moved by special muscles, but their function is doubtful. They may 

 aid in moving food through the gizzard. The caecal epithelium, like- 

 that of the stomach, digests and absorbs. In both there are special 

 groups of absorbing cells. The tracheal end cells absorb fatty products 

 from the lumen of the crop, and the peritracheal cells from the blood. 

 The tracheae themselves never normally contain fat, but in certain, 

 tracheffi there is commonly a sticky substance of uncertain origin, often 

 containing leucocytes. J. A. T. 



Pathological Effects of Phthirus pubis. — G. H. F. Nuttall, 

 {Parasitology, 1918, 10, 375-82) notes that the Crab-louse is not known 

 to serve as the vector of any infective disease, and that its pathological 

 effects on man are on the whole of slight degree. It may induce 

 pruritus. It induces pale bluish-grey maculge, but not invariably. 

 These mark the site of the insect's bite ; they appear eight to twenty- 

 four hours after the louse commences to feed on the spot affected. They 

 usually disappear in about a week after the removal of the parasite.. 

 They may be due to extravasated and altered blood. Apart from the 

 macular a febrile condition of the skin may be brought about, and the 

 lesions due to scratching may lead to secondary skin infection with 

 pyogenic bacteria. J. A. T. 



Collembola of Abor Expedition. — George H. Carpenter {Records- 

 Indian Museum, 1917, 8, 561-8, 3 pis.), reports on a collection of 

 Spring-tails from the Abor hills and elsewhere. A description is given 

 of Cyphoderopsis Jcempi, g. et sp. n., a blind pale form found under 

 stones at Rotung, N.E. Assam. It seems to be in many respects a 

 connecting link between typical Cyphoderini and the Paronellini. A 

 number of new species of Faronella, Lepidocyrtus, and Protanura are 

 dealt with. J. A. T. 



Caudal Gills of Larvae of Zygopterid Dragonflies.— R. J. Tillyard 

 {Proc. Linn. Soc. N.S.W., 1917, 42, 31-112, 6 pis., 32 figs.) has made 

 a detailed study of these structures. There is a median gill formed 

 from the appendix dorsalis, a median out-growth from the eleventh 

 abdominal tergite. There are two lateral gills formed from the two. 

 cerci of the eleventh segments, and homologous with crustacean uropods. 

 Each caudal gill is a hollow out-growth of the body-wall, with cuticle 



