368 



BIOLOGY OF THE PROTOZOA 



other vertebrated animals. Like the two preceding genera it has 

 two significant phases— a nectomonad, Leptomonas-Yike, swimming 

 phase in the invertebrate gut and in the vertebrate blood, and a 

 quiescent phase equivalent to the haptomonads of Leptomonas and 

 Crithidia. Unlike these haptomonads, however, the quiescent phase 

 is not passed as celozoic forms on the outer surfaces of cells but 

 as cytozoic forms within the cells, not only of the gut, but of prac- 

 tically all types of cells throughout the body. This leads to cell 

 hypertrophy and disintegration with a corresponding upset of 

 function. • 



Fig. 170. — Protomonads. A, B, Herpetomonas musca-domesticce; C, resting 

 stage of same; D, Crithidia subulata, nectomonad; E, resting forms of same; F, 

 haptomonads of same attached to epithelial cells; (d) basal bodies; (k) parabasal 

 body; (/) nucleus. (From Calkins after Prowazek and Leger.) 



The fully-developed organism is of the Leptomonas type (Fig. 

 169, F; 170, D). This stage occurs in the digestive tract of inverte- 

 brate hosts and in the blood of vertebrates, also in cultures. As 

 cytozoic parasites they appear primarily in macrophages and other 

 blood elements, and in cells of the liver and spleen, where they mul- 

 tiply by division, a single cell often containing 100 or more (Fig. 

 169, E). 



Early reports of the parasite interpreted them as spores of peculiar 

 organisms (macrophages) in the blood (Cunningham, 1885) or as 

 Sporozoa furunculosa (Firth, 1891). Their correct interpretation 



