196 SUMMARY OF CURRENT RESEARCHES RELATING TO 



proper unilateral illumination may still induce turning either to the 

 right or the left, showing that the movements of the legs may be con- 

 trolled by impulses received from either eye. Moreover, the response 

 depends in part upon the location of the stimulus on the eye, and not 

 solely upon the magnitude of the stimulus. In short, the process of 

 orientation may be more complicated than is implied in the theory of 

 unequal illumination and resulting difference of tonus. J. A. T. 



Oviposition of Gastrophilus nasalis. — A. E. Cameron {Science, 

 1919, 49, 2G). It is denied that this bot-fly darts at a horse's lips and 

 leaves eggs there, as C. H. Townsend stated. The eggs of G. nnsalis 

 are deposited on hairs of the throat. The adult fly strikes at the hairs 

 of the skin between the mandibles, and sometimes on the hairs of the 

 cheek. The clasping stalk of the ^gg of G. hsemorrhoidcdis, which is 

 invariably found attached to the short hairs of the lips, often appears to 

 penetrate the skin. This is not really the case, but the clasping stalk 

 may sometimes enter the hair follicle. J. A. T. 



Behaviour of Larvae of Corethra punctipennis. — Chancey Juday 

 (Froc. Amer. Soc. Zool. in Anat. Record, 1920, 17, 340). In the deeper 

 portions of Lake Mendota these larvge are very abundant ; more than 

 30,000 per square metre have been noted. The larger larva3 burrow 

 during the day in the mud (in anaerobic conditions for two months in 

 summer) ; at night they occupy the water, and may ascend to the surface 

 — a vertical migration of 25 metres. The pupge do the same. The 

 small larvse occupy the lower water in the daytime for a week or two, 

 migrating upwards at night. J. A. T. 



Olfactory Sense in Orthoptera. — N. E. McIndoo {Proc. Amer. Soc, 

 Zool. in Anat. Record, 1920, 17, 3-41-2). In grasshoppers and crickets 

 there are olfactory pores on the first and second segments of the antennae. 

 When the antennae are cut off through the third segment the reaction 

 time to odours is increased. The average reaction time of the intact 

 grasshoppers is 8 • 4 seconds, after mutilation 9 seconds. The average 

 reaction time of the intact crickets is 8*8 seconds, and after mutilation 

 10-2 seconds. J. A. T. 



Variation in Venation of Panorpa communis. — L. Mercier {G.R. 

 Soc. Biol, 1919, 82, 1168-70). The radial nervure in the genus 

 Panorpa has a single sector, which often gives off four branches, and often 

 three in P. communis. The character may be regarded as at present 

 quite unfixed. J. A. T. 



Bed-bug. — Bruce F. Cummings (Pnhlications British Museum, Nat. 

 Hist., Economic Series, 1918, No. 5, 1-20, 7 figs.). A very clear account 

 of the external structure and the habits of Cimex Jectularius, with 

 particular reference to its mode of sucking blood. The life-history is 

 sketched, and the possibility tliat it spreads disease-germs is discussed. 

 The blockage of the gut with bacteria that occurs in the rat-flea is not 

 likely to occur in the bed-bug ; so it is not very probable that the trans- 

 mission of diseases by bed-bugs is of general occurrence. Remedies are 

 duly dealt with. J. A. T. 



