NOTES ON CERTAIN PARASITIC PROTOZOA 25 



Parthenogenesis. An important fact that Schaudinn has observed 

 in T. noctucz is parthenogenesis. 1 This mode of reproduction is most 

 familiar to us in insects such as bees and aphides. He found that 

 the female form of T. noctua outlasted the males and neuters when 

 infected gnats were starved and kept on ice. Under such circum- 

 stances the females pass between the epithelium and the elastico- 

 muscular layer ; their flagella disappear, causing these flagellates to 



FIG. 7. THE ASEXUAL OR ' INDIFFERENT' MODIFICATION OF TRYPANOSOMA 

 NOCTU/E IN THE BLOOD OF THE OWL. (After Schaudinn.) 



The numerals i, 2, 3 are placed above outlines representing red blood-corpuscles of 

 the owl. , Marks the youngest stage of an asexual trypanosome adhering to 

 the corpuscle by its anterior end ; the parasite b has withdrawn its flagellum 

 and Gome to rest ; c t a parasite forty-eight hours after the stage b ; </, parasite 

 escaping in a gregarinoid form ; e t the same parasite as d after its flagellum 

 has developed ; /, resting gregarinoid form adhering to the corpuscle 3, five 

 days after the stage a ; g, full-grown trypanosoma. 



resemble gregarines. Infected gnats that have survived the winter 

 contain such parasites. In spring the parasites multiply partheno- 

 genetically, and pass into the gnat's ovary, and the eggs and ensuing 

 generation of gnats are thus infected. 



The most prominent symptom of human malaria, the attack of 



1 The occurrence of parthenogenesis in the malarial parasites has been referred 

 to Chapter I., p. 2. 



