THE MALARIAL PARASITES OF MAN 157 



real malarial parasites in November, 1880, by the military doctor A. Laveran 1 in 

 Constantine (Algeria), at first met with violent opposition, even after Richard 

 (1882) had confirmed it and Marchiafava, Celli, Grassi and others, had 

 further extended it. Not that the existence of structures found in the blood of 

 malaria patients by Laveran and Richard was denied ; on the contrary, the investiga- 

 tions of the opponents furnished many valuable discoveries, but the organisms were 

 differently interpreted and considered to be degeneration products of red blood cor- 

 puscles. Only when Marchiafava and Celli (1885) saw movements in the parasites, 

 which Laveran called Oscillaria malarice and later Hcematozobn malarice., was their 

 animal nature admitted and the parasites were named Plasmodium malarice. Shortly 

 before this, Gerhardt (1884) had stated that the disease could be transmitted by the 

 injection of the blood of a malarial patient to a healthy person. 



This supplied the starting point for further investigations, which were made not 

 exclusively, but principally, by Italian investigators (Golgi, Marchiafava and Celli, 

 Bignami and Bastianelli, Grassi and Feletti, Mannaberg, Romanowsky, Osier, 

 Thayer and others). In 1885 Golgi described the asexual cycle in the blood, 

 in the case of the quartan parasite. These investigations, after attention had been 

 drawn by Danilewsky (1890) to the occurrence of similar endoglobular parasites in 

 birds, were extended to the latter (Grassi and Feletti, Celli and Sanfelice^Kruse, 

 Labbe and others). 



The result was as follows : Malaria in man (and birds) is the result of peculiar 

 parasites included in the Sporozoa by Metchnikoff, which parasites live in the erythro- 

 cytes, grow in size and finally " sporulate," that is, separate into a number of " spores " 

 which leave the erythrocytes and infect other blood corpuscles. Morphologically and 

 biologically several species (and respectively several varieties) of malarial parasites 

 may be distinguished, on which the different intermittent forms depend. Trans- 

 mission of the blood of patients to healthy people produces a malarial affection which 

 corresponds in character to the fever of the patient from whom the inoculation was 

 made. The combined types of fever (tertiana duplex, quartana duplex or triplex) 

 are explained by the fact that the patient harbours two or three groups of parasites 

 which differ in their development by about twenty-four hours, whilst the irregular fevers 

 depend on deviation from the typical course of development of the parasites. In 

 addition to stages of the parasites which could easily be arranged in a developmental 

 series concurrent with the course of the disease, other phases of the parasites also 

 became known, such as spheres, crescents, polymitus forms, which seemed not to be 

 included in the series and, therefore, were very differently interpreted. 



The decision reached at the beginning of the last decade of the last century, which 

 found expression in comprehensive statements (Mannaberg, Ziemann and others), 

 only concerned a part of the complete development of the malarial parasites. No one 

 could with any degree of certainty demonstrate how man became infected, nor were 

 there reliable hypotheses based on analogy with other parasites concerning the exit 

 of the excitants of malaria from the infected person and their further behaviour. 

 Numerous hypotheses had been advanced, but none was able to elucidate the 



1 The discovery of Laveran is in no way lessened by the fact that one investigator or 

 another (according to Blanchard [Arch, de Paras., vii, 1903, p. 152], P. F. H. Klencke 

 in 1843) had seen, mentioned and depicted malarial parasites. (Neue phys. Abhandl. 

 auf. selbstand. Beob. gegr., Leipzig, 1843, p. 163, fig. 25). In 1847 Meckel had recognized 

 that the dark colour of the organs in persons dead of malaria was due to pigment. Virchow 

 in 1848 stated that this pigment occurred in blood cells. Kelsch in 1875 recognized the 

 frequency of melaniferous leucocytes in the blood of malarial patients. Beauperthuy (1853) 

 noticed that in Guadeloupe there was no malaria at altitudes where there were no " insectes 

 tipulaires," and suggested that the disease was inoculated by insects. 



