90 



within 10 days. Cold, especially intermittent cold, therefore does 

 little harm to larvae unless they are actually in ice, though their 

 development is retarded. Feeding is another factor in development, 

 which is much prolonged when the food-supply is limited. Develop- 

 ment from winter eggs kept in a sunny but unheated room from April 

 onwards required 50-60 days ; under the same conditions from summer 

 eggs laid at the end of May it needed 35-38 days ; 30-32 in June ; 28 

 in July ; and 24 in August. In the open air these periods would be 

 slightly longer. 



Larvae and pupae did not seem to be injured in puddles at temper- 

 atures of 35°-38° C. [95°-98-6° F.], but even a short exposure to 42° C. 

 [107-6° F.] suffices to kiU the larvae, and at 45° C. [113° F.] both 

 larvae and pupae all die. This last temperature often occurs in tins 

 lying exposed on the ground. 



Larvae of A. mactdipennis die in undiluted sea-water within 2-3 

 hours of transfer from fresh water, probably owing partly to the action 

 of other salts besides sodium chloride, as a simple solution of the 

 latter only killed the larvae in 7-24 hours. Brackish water containing 

 only a little sea-water is favourable to development, and the sea-water 

 content must be increased to one-half in order to prove fatal. 



Oiling is effective except where reeds are abundant, as they absorb 

 the oil. The planting of Azolla, Lemna and other aquatic plants 

 seems to favour breeding. Better results are achieved with plants 

 requiring so much water as to cause collections of water to disappear, 

 and sun-flowers have proved very suitable in Albania for this purpose. 

 Trap breeding-places resulted in the destruction of many larvae, and 

 though nine-tenths of these were Culex, the trouble involved is very 

 shght. 



Counts made in connection with screening tests showed that an 

 increase in Anophelines preceded an increase in malaria cases by a 

 length of time exactly equal to the incubation period. In 1918 the 

 first occurrence of young adults was early in July, and malaria increased 

 in mid-July. Such a connection is only possible, however, if the 

 young adults are capable of infection on emerging and without being 

 infected from a patient. As the weather is somewhat cool in June, 

 incubation must require more than 11 days. Mosquitos that are 

 infective at the end of June have acquired infection in the middle of 

 that month, but they were then in the larval stage and only hibernated 

 females were present. It would therefore seem that young adults, 

 as well as hibernated females, are capable of transmitting infection. 



Jancso (N.). Experimentelle Untersuchungen iiber die die Malaria- 



infektion des Anopheles und des Menschen beeinflussenden 



Umstande. [Experimental Researches on the Circumstances 



influencing Malaria Infection in Anopheles and in Man.] — Beihefte 



Arch. Schiffs- n. Trop.-Hvg., Leipsic, xxv, no. 2, 1921, 48 pp., 



9 figs. [Received 15th February 1922.] 



In experiments made from 1901 to 1905 at Kolozsvar, Transsylvania, 



Anopheles maculipennis was most easily infected with Plasmodium 



praecox, which affects man most severely ; P. vivax had a moderate 



infectibility as regards the mosquito and a moderate severity in 



man ; quartan malaria had the least infectibility for the mosquito 



and the least severity in man. 



In the case of infection with P. vivax the blood of the patient may, 

 even during the first attack, harbour gametes capable of further 

 development in the mosquito. In infection with P. praecox gametes 



