COMPARATIVE TESTS OF METHODS. 20 



possibly parasitic. By this method cellulose was colored violet or 

 black, and nematode eggs brown, or at times black, with a light 

 areole where the shell showed at the periphery. As such a method 

 lessened the refractive index which makes most nematode eggs so 

 conspicuous, the use of these reagents was discontinued as giving no 

 improvement in the resulting preparations. Stubbendorff (18t)3a) 

 has noted this test and a number of others in a note on the differential 

 diagnosis of parasite eggs and plant spores. 



COMPARATIVE TESTS OF THE WRITER'S METHOD AND OTHER 



METHODS. 



For about a year comparative tests of the writer's method and other 

 methods were made in the examination of feces of various kinds. So 

 far as possible equal amounts of feces were examined and the slides 

 made from equal amounts of material. The parasite eggs and em- 

 bryos were carefully counted with the aid of a mechanical stage, and 

 the results compared. 



SMEAK METHOD. 



Comparative tests of the smear method and the writer's method, 

 some results of which are given in connection with other tests, indi- 

 cate that the smear method is much less certain and effective. A 

 diagnosis made by the writer's method would be much more complete 

 and adequate than one based on the usual ten smear preparations. 



SEDIMENTATION METHOD. 



The simple sedimentation method is so obviously inferior to 

 methods involving sieving and eentrifuging, and improved modifica- 

 tions of the sedimentation method were found so inferior to the 

 writer's method in actual test, that the simple method was not even 

 given a comparative test. 



JU'KETTE METHOD. 



A test of the sedimentation method in which the sediment was 

 taken from the bottom by means of a stopcock' did not give as good 

 results as the centrifuge method. In this test a burette of :25 cubic 

 centimeters capacity was used. Ten cubic centimeters of water were 

 first put in it. with the idea of washing the feces at the bottom of 

 the burette instead of at the top. as is commonly done where water 

 is poured over a sediment and the sediment shaken up in the water, 

 allowed to settle, and the fluid then decanted. It appeared thai in 

 this way the sediment could be taken out promptly and already 

 washed. In testing, the sediment obtained after screening and de- 



