8 METHODS OF EXAMINING FECES FOR PARASITISM. 



Stiles (1902hh, 19031, lOOCa), is one commonly used by physicians 

 (Jones, 1907, et al.), and was used by Garrison, Ransom, and Steven- 

 son (1903a), and Stiles and Garrison (1906a) in Washington, and by 

 Garrison (1908) in Manila. 



SEDIMENTATION METHOD. 



The simplest modification of this method consists in allowing the 

 feces, if sufficiently fluid, to settle, and then examining the sediment; 

 if the feces are too solid for this, large or small amounts are washed 

 in a sufficient quantity of water, decanted as long as any matter will 

 float, and the sediment finally examined. Stiles, in the papers just 

 cited, Braun (Braun and Liihe, 1909), Garrison (1910), Letulle 

 (1905), Jones (1907), and others have advocated this sedimentation 

 method. 



BURETTE METHOD. 



I am informed by Dr. Ransom that one writer, in an article to 

 which I have not a reference at present, has varied the preceding 

 method by taking the sediment from the bottom, through a stopcock, 

 a method designated in this paper as the burette method. 



CENTRIFUGE METHODS. 



Another variation of the sedimentation method is to use a centri- 

 fuge for the purpose of giving a more rapid and certain concentra- 

 tion of material. Pepper (1908) states that he has found repeated 

 centrifuging, in which the sediment is shaken up each time with 

 some fresh water, very useful. This is the process commonly known 

 as washing. Bass (1909) uses the same device as part of his method. 

 Braun (Braun and Liihe, 1909) notes that under certain circum- 

 stances the sediment may be centrifuged after sedimenting and 

 decanting. He does not state under what circumstances this is to 

 be done. Letulle (1905) admits the use of the centrifuge if needed, 

 but objects to it on the ground that certain eggs suffer mechanical 

 injury from its use. Stiles (190'2hh. 19031) states: "The centrifuge 

 does not appear to be of any special value in fecal examinations." 



SIEVE METHODS. 



Another variation of technique consists in the use of one or more 

 sieves or screens to take out coarse particles of undigested food and 

 similar objects. Stiles (1902hh, 19031) gives a qualified indorse- 

 ment of this method in the following terms: 



In case an unusually large amount of large, coarse material is present in the 

 feces, it is sometimes convenient to pour the entire mass through a sieve, re- 



