406 BIOLOGY OF THE PROTOZOA 



about a month; toward the end of the time oocysts were found in 

 the feces and these lasted for several days, after which they disap- 

 peared and recovery was complete. Similar symptoms and similar 

 cysts have been found by a great number of observers in many 

 different parts of the world. The great wonder is that there are 

 not more cases of coccidian enteritis. 



Hemosporidia.— The Hemosporidia are Coccidiomorpha which 

 have become adapted to life in the blood, and with this mode of 

 life the more common contaminative mode of infection is replaced 

 in general by the inoculative method. With this change, new and 

 far-reaching adaptations have been developed which modify to a 

 considerable extent the typical life history of the Coccidiomorpha. 

 One structural change of great importance is the entire loss of 

 protective capsules— oocyst and sporocyst— which, if present, would 

 make activity in the blood impossible. 



Theoretical considerations as to the mode of origin of Hemospor- 

 idia and of blood parasites generally have already been considered 

 (see p. 361). Possibility of the origin from the gut of the same host 

 is indicated by some types of Coccidia where infection is contamina- 

 tive (Hepatozoon, Shellackia and Lankesterella, see Key, p. 566). 

 Here infection of the second host is also contaminative, in these 

 cases through infected blood. With Hemosporidia, fertilization 

 by union of gametes and development to the sporozoite take place 

 in the invertebrate host and the sporozoites are inoculated directly 

 into the blood of vertebrates. 



So far as the hematozoic sporozoan parasites of man are con- 

 cerned the Plasmodiidae and the Piroplasmidae alone are important, 

 the former including the malaria-causing organisms of man and 

 birds. 



The cause of malaria, although sporadically seen prior to 18S0, 

 was first recognized as a definite organism in that year by A. Laveran, 

 a French medical officer, when he discovered the phenomenon of 

 "flagellation" which we now know is microgamete formation. At 

 that time very little was known about blood-infesting Sporozoa, 

 although ten years before Lankester had observed parasites in 

 frog's blood which were later known as Lankesterella ranarum. 



The generic name Plasmodium was given by Marchiafava and 

 Celli in 1SS5. Laveran had named the organism Oscillaria malariae, 

 but since the name Oscillaria was pre-occupied, the first-recognized 

 cause of malaria became Plasmodium malariae, Laveran. Golgi 

 (1886) showed that there are different types of life history in the 

 blood and suggested the possibility of different species. This was 

 made the basis of Grassi and Feletti's (1890) division of the malaria- 

 causing forms into Plasmodium vivax, Grassi and Feletti, P. malar i ae 

 and Laverania malariae. These observers believed, with some 

 justification, that the clinical features of pernicious malaria, also 



