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circumstances, when trooops that include many malaria-carriers are 

 being constantly brought into France, it has been thought well to 

 study the value of these theories regarding the immunity of races of 

 Anophelines. The author, by means of experiments which are here 

 detailed, has demonstrated the receptivity of Anophelines in the Paris 

 district to the two forms of tertian malaria ; infection has been pro- 

 duced by Plasmodium vivax in 9 individuals of A. maculipennis out of 

 23, and by P. praecox in 8 out of 15. Further experiments have proved 

 that these Anophelines are capable of transmitting the infection they 

 have received. It is therefore obvious that the absence of malarial 

 infection in the region studied is not due to immunity of the mosquitos 

 occurring there. 



The author's observations have led to certain deductions concerning 

 the sexual development of malarial organisms of the tertian type. 

 The varied conditions of humidity and temperature in which his 

 experiments have been conducted show that the infection of mosquitos 

 is not influenced by exterior circumstances if the temperature necessary 

 to the development of the forms is maintained. The infection con- 

 tracted by the mosquitos has been no more intense in moist than in 

 dry air. While dryness in the air is directly harmful to AnopheUnes 

 and does not admit of their prolonged existence, the sporocystic 

 development of the parasites continues unimpaired. The action 

 of temperature is apparent in the rapid development of the parasites. 

 The only conditions that seem to influence development in the mosquito 

 depend upon the state of the parasites in the blood of the malaria 

 patient. Certain gamete-carriers are infective to mosquitos, others 

 are not ; and while there is no exact explanation of this, it apparently 

 depends upon the age and sex of the gametes. When a malarial 

 subject harbours gametes capable of sexual development, it may be 

 said that all healthy Anophelines that draw blood from that source 

 contract infection. This is borne out by the author's experiments. 

 In one case of malignant tertian malaria, none of the five mosquitos 

 fed upon the patient became infected. It was found impossible to 

 discover the existence of male crescent forms among the numerous 

 female crescents in the blood of this patient. It may be admitted 

 therefore that the elimination of one sex of the gametes, if it could 

 be obtained by suitable treatment, would render great service in 

 prophylaxis in the absence of a more effective cure. According to 

 Ziemann, male crescents can easily be destroyed by quinine, to which 

 the female crescents are resistant. This theory has not, however, 

 met with universal acceptance. 



The infection obtained in the Parisian Anophelines has in general 

 been more intense with P. praecox than with P. vivax. All infections 

 with the latter have been weak ; with the former, infection of the 

 mosquito has been severe, the salivary glands being overcharged with 

 sporozoites. The study of the sexual evolution of P. vivax and 

 P. praecox affords valuable evidence in support of the question of the 

 specific difference of these forms. While in human blood the epidemio- 

 logic succession of the two tertian forms has been so striking as to 

 lead many authors to regard them as two varieties of the same parasite, 

 in the mosquito, on the contrary, the cycle of each form exhibits a 

 constant individuality, both in morphological and physiological 

 characters. The characteristics of the living young zygotes of the 



