H^MOSPORIDIA 159 



" Contrarily to the fungi, announced previously by the same authors, these 

 yeasts do not become pathogenic to the culicids ; neither can one, according to 

 them, attribute any role whatever in the aptitude of Stegomyia calopus for 

 transmitting yellow fever. 



" Nevertheless the study of these yeasts is not devoid of interest : the spherical 

 or irregular masses formed by these yeasts, which one encounters in the large 

 air-sac of the culicid, may be easily taken, upon superficial examination, for 

 sporozoans, and the authors are not far from supposing, as we shall see farther 

 on, that these yeasts were taken by the Americans Parker, Beyer and Pothier, 

 for one of the stages of the parasite which they described under the name 

 Myxococcidium stegomyiw. It is well to indicate, now, the possible errors of 

 interpretation to which the encountering of these yeasts, parasites of culicids, 

 can give place. 



" Schaudinn, in his remarkable work, interprets in a wholly individual man- 

 ner the role of these yeasts, which he nearly always found in the diverticula of the 

 stomach (air-sac, sucking stomach, food reservoir) of the numerous culicids 

 which he dissected in the course of his beautiful researches. According to him 

 these yeasts have a purely physiological role : by his investigations he has been 

 led to conclude that the irritating effect of the bite of Culex is due, not alone, 

 as it had been thought up to now, to the saliva secreted by the salivary glands, 

 but as well to the combined action of gas and diverse products, secreted by the 

 yeasts of the oesophageal diverticula. We will not follow the author in his very 

 concise demonstration of this role of the yeast parasites in any physiological way ; 

 we have only to mention this original interpretation in passing, which shows us 

 how much all these questions of the parasites of culicids need to be seriously 

 studied. We see in fact, on the subject of these yeasts of the stomach of the 

 mosquito, three authors, studying them successively in different countries, 

 Schaudinn in Germany, Parker, Beyer and Pothier in Mexico. Marchoux, 

 Salimbeni and Simond in Brazil, and each one of them attributing a totally 

 different interpretation from the viewpoint of their parasitic role." 



ANIMALS. 



PROTOZOA. 

 Parasites of mosquitoes belonging to the Sporozoa and Flagellata have been 

 described by many authors. Among the Sporozoa are Myxosporidia, Haemo- 

 sporidia and Gregarina3. To the liimnosporidia belong the malarial and other 

 blood parasites of mammals and of birds. These are grouped in the family Plas- 

 modidae and, as is well known, have a life-cycle which necessitates two hosts. The 

 agamic phase is passed in the blood of a vertebrate, the sexual phase in some 

 blood-sucking insect. These parasites are discussed in a later chapter, in con- 

 nection with malaria (p. 188). A nearly related group of Hgemosporidia is the 

 family Haemogregarinidas, a large proportion of which live in cold-blooded 

 animals (reptiles, batrachians and fishes) but also some in warm-blooded 

 animals (mammals and birds) . It was in a species of this group, an Hcemopro- 

 teus from the crow, that MacCallum was the first to prove the existence of sexual 

 phases in the Haemosporidia. Several Haemogregarinidae are known to be 

 transmitted by mosquitoes. According to Schaudinn, Hcemoproteus noctuce, a 

 blood-parasite of owls, is transmitted by Culex pipiens. Another species, 

 Hcemoproteus danilewsTciji, and probably still other species, all living in the blood 



