UNIVERSITY OF CALIFORNIA PUBLICATIONS 



ZOOLOGY 



Vol. 16, No. 2, pp. 23-29, 1 figure in text 



November 19, 1915 



In*>.>,, 



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DEC 30 1916 



ON GIARDIA MICROTI SP. NOV., FROM THE ^^^iiLo^i-! i^ 

 MEADOW MOUSE 



CHARLES ATWOOD KOFOID and ELIZABETH BOHN CHRISTIANSEN 



The systematic examination of a series of rodent hosts for the 

 detection of Giardia niuris (Grassi) has brought to light in Microtus 

 calif ornicus calif ornicus (Peale) a species ' differing in appearance, 

 proportions, and stainability from the widely prevalent G. mnris, and 

 not possessing the characteristics of any known species of the genus. 

 The hosts were taken in traps set in Strawberry Canon on the Tni- 

 versity campus. Of the six hosts examined three only were infected 

 with Giardia, two males and one female, the parasites occurring in the 

 duodenum, ilium, and colon, and in one instance in the rectum also. 



This species was not detected in 98 culture mice, both white and 

 gray, in 42 culture rats, in 12 Belgian hares, in 59 Peromyscus 

 maniculatjis gambeli (Baird) trapped in the .same general region as 

 the host Microtus, nor in two coyotes {Canis ochropus ochropus 

 Eschcholtz) trapped in the same canon with Microtus and presumably 

 feeding upon them and often tearing open or carrying off our traps. 

 Nor was G. muris found in any of the six Microtus examined. 



They cause an inflation of the intestine, whose walls become thin 

 and flaccid, and assume a yellowish-orange color in the infected region. 

 An abundance of material was secured in various stages of binary 

 and multiple fission and in encystment. including the so-called 

 "copulation cysts," and cysts in which nraltiple fi.ssion had produced 

 a 16-nucleate pla.smodium or somatella. 



The material has been prepared by the wet method from smears 

 well rubbed out from the intestinal epithelium, fixed in hot Schau- 

 dinn's fluid, and stained in iron haematoxyliu. 



