576 RONALD EOSS AND R. FIELDING-OULD. 



been scrupulously studied and have given rise to a mass of 

 literature already very large. The sexual functions of the 

 gametocytes — which can be witnessed in vitro, — originally 

 observed by MacCallum, have been seen also by Koch and 

 Marchoux ; while the facts are confirmed by the cytological 

 studies of Bignami and others. The development in the 

 gnat and the infection of the healthy vertebrate host by the 

 bite of the gnat, originally established by one of us, have 

 been confirmed by Daniels, Koch, Grassi, Bignami, Bastia- 

 nelli, and many others, and are accepted by Laverau, Ray 

 Lankester, Metschnikoff, Manson, Celli, and other distin- 

 guished men of science. A full history of the subject of the 

 relation between malaria and gnats, together with a complete 

 bibliogi*aphy, has been written by NuttalL* 



The terminology used above was arranged in consultation 

 with Professor Herdman, F.R.S. It has been adopted by 

 Laveran and Manson. Grassi and others had previously 

 employed the terms gamete and zygote, but used sporo- 

 zooid for the bodies we call blasts. We use the word 

 blast somewhat in the sense employed in embryology, and 

 as synonymous with sexually produced spores. Bay 

 Lankester suggests for them the name filiform young. 



It should be added that, within the capsules of mature 

 zygotes large black bodies (fig. 67) are often to be found. 

 It is doubtful whether these have any real connection with 

 the parasites. 



We divide the H^mamcebid^e into two genera ('Nature,^ 

 August 3rd, 1899), namely — 



Genus I. Hfemamoeba, Grassi and Feletti. The gameto- 

 cytes have a shape like that of the sporocytes before the 

 spores have been produced. 



* Nuttall, ' Hygienisclie Rundschau,' numerous papers, 1898, 1899, 1900. 

 Also "On the Role of Insects .... in the Spread of Diseases," ' Johns Hop- 

 kins Hospital Reports,' Baltimore, vol. viii. 



The most recent flgures of stages of the malaria parasites are those published by 

 Koch, ' Zeitschrift fiirHyg. und Infect.,' 1899 (photographs) ; Grassi, Bignami, 

 and Bastianelli, 'Annalid 'Igiene sperimentali,' 1899 (])]ates) ; "Sierra Leone 

 Expedition," 'Thompson Yates Laboratories Report,' vol. ii (photographs). 



