SPOROZOA 103 



sporidae, in 1880, as an organism always to l)e found in the 

 blood of patients suffering from malarial fever ; this received the 

 rather inappropriate name of Plasmodium, which, by a pedantic 

 adherence to the laws of priority, has been used by systematists 

 as a generic name. Golgi demonstrated the coincidence of the 

 stages of the intermittent fever with those of the life-cycle of the 

 parasite in the patient, the maturation of the schizont and 

 liberation of the sporozoites coinciding with the fits of fever. 

 Manson, who had already shown that the Nematodes of the 

 blood that give rise to Filarial haematuria (see Vol. II. p. 149) 

 have an alternating life in the gnats or mosquitos of the common 

 genus Cuhx} in 1896 suggested to Eonald Eoss that the same 

 might apply to this parasite, and thus inspired a most successful 

 work. The hypothesis had old prejudices in its favour, for in 

 many parts there was a current belief that sleeping under 

 mosquito - netting at least helped other precautions against 

 malaria. Eoss found early in his investigations that Cvlex was 

 a good host for the allied genus Hmmofrotcus or Proteosoma, 

 parasitic in birds, but could neither inoculate man with fever 

 nor be inoculated from man. He found, however, that the 

 malaria germs from man underwent further changes in the 

 stomach of a " dappled-wing mosquito," that is, as we have since 

 learned, a member of the genus Anopheles. Thenceforward the 

 study advanced rapidly, and a number of inquirers, including 

 Grassi, Koch, MacCallum (who discovered the true method of 

 sexual union in Haltcridium "), and Eoss himself, completed his 

 discovery by supplying a complete picture of the life-cycles of the 

 malaria-germs. Unfortunately, there has been a most unhappy 

 rivalry as to the priority of the share in each fragment of the 

 discovery, whose history is summarised by Nuttall, we believe, 

 with perfect fairness.^ 



The merozooite is always amoeboid, and in this state enters 

 the blood corpuscle ; herein it attains its full size, as a schizont, 

 becoming filled with granules of " melanin " or black pigment, 

 probably a decomposition product of the red colouring matter 

 (haemoglobin). The nucleus of the schizont now divides re- 



^ There is no difference between a mosquito (little fly) and a gnat, both names 

 are applied indiscriminately to thin-bodied Diptera of the group Nemocera which 

 attack man ; only tlie females bite (see Vol. VI. pp. 466-468). 



- Regarded by Schaudinn as a state of the Flagellate Trypanosoma (p. 119 f.). 



* In Qtiart. Journ. Micr. Sci. xliv. 1901, p. 429. 



