266 SPOROZOA. 



may be so numerous as to be actually in contact with one 

 another on the stomach-wall. 



Remarks. — There is a vast literature on this, as well as the 

 other species causing malaria in man, and it is difficult to 

 refer to even the more important works here. Sinton (1929) 

 has pubhshed a very valuable and complete bibliography 

 on malaria in India, indexing about 2200 papers and reports 

 dealing with the causation, prevention, and treatment of the 

 disease. Covell (1927, 1931) has similarly collected all the 

 available data relating to the transmission of malaria by 

 different species of Anophehne mosquitoes. For information 

 on the subjects of pathology of malaria infections, the occur- 

 rence and mechanism of relapses, the factors which influence 

 the development and survival of malarial parasites in 

 mosquitoes, the possibility of animal reservoirs and the 

 susceptibility of man and animals to inoculation, reference 

 may be made to text-books and other special works. 



L. malarise is usually present in tropical countries, and is 

 responsible for severe outbreaks of epidemic malaria. The 

 fever is referred to as malignant, as it does not yield readily 

 to treatment. Two types are kno\^Ti, a quotidian, which 

 recurs every day, and a tertian, which recurs every other day. 

 Whether or not these are due to distinct species or the 

 quotidian is due to double infection is still uncertain. 



Knowles (1919) noticed crescents, without asexual forms, 

 in blood -films taken from a convalescent malaria patient. 

 It is quite common to come across crescents and other forms 

 in blood- films from persons Kving in an endemic area who are 

 quite free from all symptoms of malaria at the time. Knowles, 

 Chopra, Gupta, and Das-Gupta (1923) record the examination 

 of twelve villagers from the Kuki Hills in Assam admitted to 

 hospital in Calcutta suffering from framboesia. All except 

 one were afebrile, and yet blood examination showed that 

 eleven out of twelve patients harboured malarial parasites, 

 all three species being found among different patients, and both 

 trophozoites and gametocytes were encountered. Sinton 

 (1926) has made a thorough study of the problems relating 

 to gametocyte formation. He finds that (a) there is a marked 

 seasonal variation in crescent production in patients ; (6) differ- 

 ent localities show a different proportion of crescent- carriers ; 

 (c) there is a distinct correlation between the numerical pre- 

 valence of asexual forms in the peripheral blood and the number 

 of crescents which appear about ten days later ; {d) the 

 development of crescents appears to be associated with a 

 lowered immunity, possibly due to a change in the reaction 

 of the pulp in the bone-marrow and spleen ; (e) no marked 

 correlation can be traced betAveen the degree of splenic enlarge- 

 ment and the occurrence of crescents in the peripheral blood ; 

 (/) duration of life of a crescent may be as long as forty to 



