GASTEIUER'S AND BASS'S METHODS. 9 



jecting the portion left in the sieve; or to \vsish the feres in a sieve, holding 

 the latter under water. As a rule, however, the sieve is not very useful in fecal 

 examinations. 



On the other hand, the use of the sieve receives unqualified indorse- 

 ment from Cobb (1904). In examining sheep feces for fluke eggs 

 he boils a pellet or part of a pellet of sheep dung in water for a 

 few minutes; puts it in a hemispherical brass sieve of 80 to 100 

 meshes to the inch, the sieve being in a watch glass full of water, and 

 itself standing partly full of water; brushes the pellet through the 

 sieve by means of a sable brush; sediments the fluid containing the 

 fecal matter which passes through the sieve, and repeatedly removes 

 the supernatant muddy fluid with a pipette until water poured on 

 the sediment remains clear: and then brushes this sediment through 

 a sieve of miller's silk bolting cloth of five meshes to the millimeter. 

 The water which passes through the silk sieve is then examined for 

 fluke eggs. 



Bass (190!)), Telemann (1908). and Garrison (1910) use a sieve 

 of some sort in making examinations of feces. 



GASTEIGER'S FILTER METHOD. 



Gasteiger's (1904) method is an inversion of the methods where 

 a centrifuge and sieve are used. Whereas with the latter the object 

 is to screen out foreign particles larger than parasites and eggs and 

 seek for the parasitic material at the bottom of the centrifuge tube. 

 Gasteiger, in his search for eggs of Ascaris in the stalls of cattle, 

 soaks the manure, straw, and mud in water; filters this water through 

 some unspecified sort of filter, and examines the residue, not the fil- 

 trate, for eggs. This accomplishes to a lesser degree the same thing 

 that is accomplished by sedimentation, sieving, and centrifuging 

 it gives a concentration of material. 



BASS'S SALT soi.t TION METHOD. 



Bass (1906) proposed a method which consisted in putting a quan- 

 tity of feces in a vial three-fourths full of a nine-tenths saturated so- 

 lution of sodium chlorid, shaking this well, allowing it to settle, and 

 then examining a drop from the surface of the fluid. This method 

 was proposed for the examination of human feces for hookworm eggs. 

 According to Bass, all the eggs rise to the surface and large numbers 

 may be found in one drop. Of course this method depends on the 

 specific gravity of the parasite egg being less than that of the solu- 

 tion employed. AVaddell (1910) states that if an examination of 

 three slides, presumably smear preparations, did not disclose human 

 hookworm eggs, this method of Bass's was used, and says: " By this 

 method from 30 to 40 minutes could be saved per stool examined." 

 78989 Bull. 13511 1 



