508 Dr. H. B. Fantham. Herpetornonas pediculi, n. sp., [Nov. 24, 



the flagellum describes a series of circles and spirals, producing marked 

 currents in its neighbourhood. 



A very common movement is that of partial rotation of the body of 

 H. pediculi. The posterior end of the body remote from the nucleus is 

 chiefly concerned, and this portion often twists over, so that the dorsal 

 surface becomes ventral and vice versd (Plate 14, fig. 10). Sometimes a small 

 cluster of parasites may be observed, twisting simultaneously and producing 

 a general shimmering effect. 



Entanglement of two organisms by their flagella is sometimes seen. The 

 movements of the parasites then are most violent. On one occasion I saw 

 the flagellum of a small parasite torn from its body by the vigorous move- 

 ments of a much larger Herpetomonas with which it had become entangled. 

 Such intensely vigorous movements as the last-mentioned are rare. 



Life-History in Brief of H. pediculi. 

 It is of interest to trace the course of the development of the parasite 

 throughout its life in one host. The following development has been observed 

 in the living organism, and afterwards corroborated by examination of stained 

 preparations. 



In the excrement of lice infected with H. pediculi are small, oval bodies, 

 well adapted for resisting desiccation or other adverse condition. Similar 

 bcdies occur in the hind gut of the lice, where they are formed before passing 

 out with the excrement. Other lice, feeding at spots contaminated by their 

 predecessors, ingest some of these small oval post-flagellates, which consist of 

 a " varnish-like " thin cyst wall, enclosing some granular protoplasm, a 

 nucleus and a blepharoplast (Plate 14, figs. 27-29). Such cysts may also 

 be ingested by larval Pediculi. Passing with fresh blood into the fore gut of 

 a new host, the post-flagellates commence a new development, and as this 

 leads to the formation of the flagellate, it has been termed the pre-flagellate 

 stage (fig. 1). 



At first round or oval, the parasite rapidly commences to elongate, 

 the end first lengthening becoming, as a rule, the flagellar end of the 

 organism. At this period, a somewhat more refractile area can be seen in 

 life, and the finely granular chromatophile contents of this area concentrate, 

 forming a thread which ultimately reaches the surface. The thin ectoplasm 

 of the parasite is pushed forward still more by the thread, which ultimately 

 becomes free of the body and protrudes as a short flagellum (fig. 2). The 

 flagellar origin is the chromatophile area or so-called " flagellar sac," which is 

 usually in the neighbourhood of the blepharoplast, which, in the fully 

 developed organism, is always anterior to the nucleus. Growth of the non- 



