ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 569' 



Study of Crithidia leptocoridis.* — Irene McCulloch has studied 

 this Flagellate, which abounds in the intestinal tract of Leptocoris tri- 

 vittatus, the box-elder bug. In the vegetative stage it is a relatively 

 long, slightly flattened form, tapering to fine points anteriorly and 

 posteriorly. In the central part of the very hyaline cytoplasm there 

 is a large vesicular nucleus connected directly with the extranuclear 

 organelles, the rhizoplast, " kinetonucleus," flagellum, basal granules, 

 and the "axostyle." Like others of its kind, it moves vigorously ; the 

 flagellum, the body, and the undulating memlu'ane, all assist in pro- 

 gression. There is a very rapid vibration of the rigid body from side to 

 side, combined with spiral movements of the flagellate end of the body, 

 either to the right or to the left. Then an instant follows in which the 

 spiral movement alone is in evidence. An instant later the flagellate 

 end whips around and the organism darts off in another direction. The 

 parasites were seen boring their way foi' at least one-third of their body- 

 length into the Malpighian tubules. 



The author describes the longitudinal binary fission of the vegetative 

 phase. The life-cycle is divided into three stages : preflagellate (in 

 the stomach), flagellate (vegetative forms in mid-intestine), and post- 

 flagellate (in the rectum). The box-elder bugs seem to be casually 

 infected by means of spores or moist excreta taken up with their food, 

 which consists of the juice of the box-elder and maple-trees, and the 

 fruit of the raspberry. Under laboratory conditions, when food was 

 scarce, a vigorous insect has been seen sucking the digestive tract of a 

 weakened one. There was no evidence of infection of eggs. The per- 

 centage of infection increases with age, and almost all adults are infected.. 



* Univ. California Publications (Zool.) xvi. (1915) pp. 1-22 (4 pis. and 1 fig.).. 



Dec. 20tK 1916 2 R 



