127 



in 24 hours ; the gas which is formed soon diffuses into the air. The 

 opportunities for the employment of this method are however very- 

 limited. 



In a note the Editor of the Tropical Diseases Bulletin points out 

 that in 1911 Koss and Edie found that potassium cyanide in water, 

 1 in 300,000, was effective experimentally, larvae of Oulex and Anopheles 

 being killed by it. It was mixed with floating soap and the whole 

 compressed into tablets. The method was tried in Ceylon, but a 

 strength of 1 in 37,000 was found to be required, and this concentration 

 was considered to be risky. 



Russell (F. F.). Summary and Discussion of the Work performed 

 at the Board of Health Laboratory during the Calendar Year 1916. 



— Proc. Med. Assoc. Isthmian Canal Zone, x, no. 1, January-June 

 1917, pp. 7-25. PubUshed by the Panama Canal Health Dept. 



A table shows the numbers of the various species of mosquitos 

 captured m different parts of the Isthmus of Panama during the year. 

 Taeniorhynchus {Mansonia) titillans accounted for 242,900 out of a 

 total of 391,300. The other figures were : Anopheles albimanus 

 55,365 ; A. tarsimaculatus 3,813 ; A. argyrotarsis 4 ; A. pseudopuncti- 

 pennis 45 ; A. apicimacula 19 ; A. malefactor 114 ; Taeniorhynchus 

 {Mansonia) fasciolatus 265 ; T. (M.) nigrica7is 67 ; Ochlerotatus {Aedes) 

 taeniorhynchus 2,154 ; Aedomijia squamipennis [45] ; Lutzia allostigma 3 ; 

 Stegomyia fasciata (calopus) 2,068 ; Culex and allied genera 76,145 ; 

 Wyeomyia 990 ; Lesticocampa 62 ; Psorophora 35 ; Deinocerites 36 ; 

 Sabethes 1 ; Johlotia 11 ; Haemagogus 3 ; and damaged Anopheles 7,155. 



Much information is given regarding the plant, Pistia stratiotes, 

 attached to which T. titillans passes its entire larva and pupal life 

 beneath the surface of the water. The breathing tubes of both larva 

 and pupa are so modified as to be able to pierce the rootlets of 

 P. stratiotes and obtain oxygen direct from the plant. Its roots are 

 sometimes several feet ui length and they hang straight downward in the 

 water with a quantity of decayed vegetable matter and debris attached 

 t^ them. In this mass of filamentous rootlets the larvae and pupae 

 of T. titillans are to be found. A negative result attended the one 

 test made to determine if this mosquito could transmit dengue fever. 



Observations on the biology of Dermatobia cyaniventris showed that 

 half-grown larvae could be successfully transplanted from one animal to 

 another. The iguana tick, Amblyomma dissimile, was found on 

 Iguana tuberculata, on 70 per cent, of the snakes recorded, and on 90 

 per cent, of the toads. 



Hirst (S.). Studies on Acari. No. 1. The Genus Demodex, Owen.— 

 Brit. Mus. Nat. His., London, 1919, 44 pp., 13 plates, 4 figs. 

 Price 105. 



The species of the genus Demodex may be present without causing 

 any inconvenience to their host and they have been frequently found 

 on perfectly healthy animals. D. folliculorum has been met with in 

 man without causing disease. Gmeiner is of opinion that these mites 

 occur in the skin of practically every human being, and 

 although not the actual cause of disease they are considered amongst 

 the possible transmitters of leprosy and other skin infections. 



