16 METHODS OF EXAMINING FECES FOR PARASITISM. 



The likelihood of finding easily identified mature worms or tape- 

 worm segments warrants a more careful examination. Garrison 

 (1910) has recognized this fact and given a method of collection as 

 follows : 



In the case of the larger worms, such as Ascaris and the large tapeworms, 

 which are easily picked out, about the only precautions needed are to clean the 

 worms of the fecal debris and to keep them as fresh as possible until they are 

 killed. This is best done by transferring them promptly from the fresh stool 

 to a dish of warm physiological salt solution. * * * 



Smaller worms, like hookworms, pinworms, whipworms, and the " dwarf 

 tapeworm," require careful searching, and this is best done by spreading por- 

 tions of the fluid stool in a thin translucent layer in a glass dish or on a glass 

 plate (table top), the glass being placed over a black background. 



In picking out the still smaller forms, such as the adult trichinae, the minute 

 intestinal fluke, Heteropliyes, and the detached heads of tapeworms, a hand 

 lens is almost necessary, and it is advisable to make a routine practice of run- 

 ning over the material with a magnifier of low power in every case. 



Should the stool not be sufficiently fluid to admit of the above manipulation, 

 it must be thoroughly mixed and diluted with water, and this brings up the 

 method of sedimentation, which, while of special use in collecting ova, is 

 frequently a valuable help in finding the smaller worms. 



THE WRITER'S METHOD. 



The writer's method includes both macroscopic and microscopic 

 examination. Concentration is attained by careful comminution of 

 feces, the use of sieves, sedimentation and centrifuging, and washing 

 in water. The result is checked by centrifuging one tube of ma- 

 terial in a calcium chlorid solution with a specific gravity of 1.250. 



The illustration (fig. 1) is intended to show at a glance the appa- 

 ratus needed (except for pipettes and brushes) and the method and 

 order of its use. It is, of course, evident that the reader will be 

 familiar with the individual pieces of apparatus. 



COMMINUTION OF FECES. 



In any method which aims at a concentration of the parasitic ma- 

 terial present it is first necessary to break up the fecal masses in 

 order to release the embedded and adherent parasites and to put 

 the feces in such shape that they can be treated by any of the proc- 

 esses outlined in the preceding part of the paper. This is a feature 

 to which it seems that too little attention is paid. Of the methods 

 of comminuting such fecal masses, boiling in water, as advocated 

 by Cobb (1904) for sheep feces, is fairly good, but not so effective 

 for sheep feces as the general method used by the writer, and has 

 obvious objections in the cases of human feces or those of the carniv- 

 ora. Stiles (1902hh, 19031) states that the feces should be shaken 

 or stirred thoroughly, and Telemann (1908) notes that the feces 



