1915] McCulIoch: Crithidialcptocoridis 3 



on a cover glass and sealing the cover glass over a hollow side with 

 vaseline. However, bacterial infection in such cultures prevented a 

 snccessful study for any length of time. 



For about one-half of the preparations observations of the living 

 material were made and recorded, then the material on both cover 

 glass and slide was fixed and stained. Frequently the smear on the 

 cover slip was stained with iron haematoxylin and the smear on the 

 slide M'ith Giemsa, making a total of eight or ten preparations from 

 a single bug. Other preparations were fixed at once without allowing 

 any time for exposure, in hot Schaudinn's fluid and stained with iron 

 haematoxylin. Dobell's iron haematein method was also of great 

 value. 



4. ACKNOWLEDGMKNTS 



To Hiss Nadine Nowlin, Assistant Professor of Zoolog\', Univer- 

 sitj^ of Kansas, through whose efforts and assistance I was able to 

 undertake this work, I wish to acknowledge my deepest gratitude, and 

 to Dr. C. A. Kofoid, Professor of Zoology, University of California, 

 I wish to express my sincere thanks for many helpful suggestions and 

 mucli valuable criticism during the past two years. 



I wish also to take this opportunity to publicly thank the several 

 people who kindly collected box-elder bugs for me in different parts 

 of the country. 



II. ilORPHOLOGY 



In the vegetative stage (pi. 2, figs. 54-56; pi. 3, figs. 57-62 and 

 text fig. A) Critliidia leptocoridis is a flagellate with a relatively long, 

 slightly flattened body, tapering gradually both anteriorly and pos- 

 teriorly to fine points. In the central part of the hyaline body there 

 is a large vesicidar nucleus connected directly with the extranuclear 

 organelles, the rhizoplast, "kinetonucleus." flagellum, basal granule 

 and the "axostyle." (text fig. A). 



The cytoplasm of this vegetative form is very hyaline and does 

 not stain uniformly. Around the "kinetonucleus" (pi. 3, figs. 57-60) 

 there is a light-staining area which extends forwards along the 

 flagellum (pi. 2, fig. 55). The crithidial forms of Schizotrypanum 

 cruzi (Chagas, 1909) show a similar area. Patton also figures such a 

 region in Critliidia gerridis (1908). Among the herpetomonads this 

 area is still more prominent. In Herpetomonas luciliae Strickland 

 (1911) and in Herpetomonas muscae domesticae Prowazek (1904) 



