COMPARATIVE TESTS OF METHODS. 29 



more in mechanically breaking up the feces by a slight amount of 

 chemical action than in actually concentrating parasitic material 

 by eliminating nonparasitic matter soluble in ether and hydrochloric 

 acid. As previously stated, the tests of the writer's method on sheep 

 feces gave a constant theoretical concentration of 4: 1. The addition 

 of ether and hydrochloric acid to a given 0..") cubic centimeter of 

 sediment so obtained gave a reduction to 0.4 cubic centimeter, or an 

 additional theoretical concentration of only f> : 4. When the ether 

 and hydrochloric acid were added to the fresh feces a somewhat 

 smaller sediment was obtained. This does not indicate a greater con- 

 centration, as it appears to, but a lesser breaking up of feces by these 

 reagents than by water, so that more agglomerations of material 

 that should be broken up to allow the finer matter to pass the sieve 

 are left unbroken, and the small as well as the large particles are 

 held by the sieve. This is evident from the result obtained by adding 

 these reagents last to determine the action due to them alone. 



Another result sometimes obtained by using Telemann's method 

 on sheep feces was that a plug of plant material formed at the top 

 of the centrifuge tube and held in its mesh almost all the fecal mate- 

 rial. The feces of herbivora are composed largely of plant matter 

 and hence largely of cellulose. This is removable to a great extent 

 by sieving but is not at all soluble in Telemann's reagents. This is 

 also true of the feces of such birds as chickens and pigeons, as tests 

 with such feces indicate. 



On the other hand, the feces of man and of the carnivora have less 

 plant matter of the sort and more matter that is soluble in ether and 

 hydrochloric acid. Nevertheless, comparative tests indicate that the 

 writer's method is practically as good as Telemann's for these feces 

 also. In tests with human feces where the writer's method gave a 

 theoretical concentration of 4:1. Telemann's method gave the same 

 result. In one case the sediment obtained by the writer's method was 

 treated by Telemann's method, and after shaking up and stirring 

 was again centrifuged. The resultant sediment showed no reduction 

 in volume as a result of the action of the chemicals. In another ca>e 

 where the writer's method gave a sediment of 0.8."> cubic centimeter.au 

 application of Telemann's method to this sediment reduced it to 

 0.05 cubic centimeter. Even more surprising result > were obtained 

 with dog feces, used as representative of feces of the carnivora. In 

 test cases sieving in water gave a concentration of 5: 1. In one case 

 the application of Telemann's method to the sediment so obtained 

 reduced it to half of its volume, thereby doubling the concentration. 

 Although the concentration was doubled, the fact that the writer's 

 method had reduced the original 1 cubic centimeter to O.i2 cubic centi- 

 meter, thereby eliminating 0.8 cubic centimeter, while the chemicals 

 had onlv reduced it bv 0.1 cubic centimeter more, indicate- that the 



