146 . University of California Publications in Zoology [Vol.18 



In my work on the detection of the cysts of Giardia microti^ a 

 species found in rodents and similar in structure and size to Giardia 

 intestinalis of man, I have used certain modifications of the Cropper 

 and Row method, which I believe are improvements not only by saving 

 considerable time in making the examination but also of enhancing 

 the accuracy of detection of the cysts of Giardia and of other Protozoa 

 in the stools. This method has been tested with success on human 

 stools in the Biological Laboratory of the California State Board of 

 Health. 



The first change in the method, and one that saves considerable 

 time, is the employment of the Hamilton-Beach ''Cyclone" electric 

 mixer for emulsifying the stools. This device may be seen in use in 

 mixing drinks at most soda fountains. It commends itself very favor- 

 ably because of its rotary action and its speed in beating up an 

 emulsion. This action favors the mingling of all parts of the stool 

 into a condition in which the cysts are uniformly distributed. The 

 instrument shortens the time of thirty minutes prescribed by Cropper 

 and Row (1917) as necessary when the stools are to be shaken into 

 an emulsion to not more than ten minutes. Naturally the time element 

 here is dependent upon the firm or the liquid consistency of the stools. 

 The action of emulsification may be accelerated by fastening a wire, 

 looped back and forth in a single plane, to the rim of the glass con- 

 taining the sample of the stool in the normal saline solution so that 

 it projects down into the mixture. This simple device is of great 

 service in that it helps to break up any lumps that may occur in the 

 faeces. I have found that this mixer beats up a fairly uniform 

 emulsion and is entirely satisfactory in liberating the cysts from the 

 lumps in the stools. This wire loop was devised by Mr. J. D. Mc- 

 Donald, Assistant in the Biological Laboratory of the California State 

 Board of Health for use in the examination of human stools for hook- 

 worm. I am greatly indebted to him for the suggestion of using the 

 looped wire in order to break up the lumps in the stools, and to 

 Professor C. A. Kofoid, Director of the Biological Laboratory of the 

 California State Board of Health, for the permission to publish this 

 note regarding the method of examination of stools in use in that 

 laboratory. 



Another change in the method is in the use of neutral red to stain 

 partially and to differentiate the cysts from tlie debris and from the 

 intestinal yeasts. The use of this stain in making diagnosis of faecal 

 material w^as first suggested by Stitt (1911) . I have used two methods 



