Apr. 15,1925 Laboratory Methods for Parasitological Investigations 775 
through to the lower screens and washes 
the contents which pass through from 
the top screen. Most of the unpleas¬ 
ant odor of the ingesta and fecal 
material (and the odor of viscera 
packed in borax for 10 days is decidedly 
unpleasant) is associated with the fine 
material which passes through the last 
screen, and this is promptly washed 
water in the dishes and examined for 
parasites that may be held on them or 
in their meshes. 
In most cases this method of 
examination shows the following ad¬ 
vantages over the sedimentation and 
washing method: There is a great 
saving of time, as washing through the 
screens is a much quicker process than 
Fig. 1 .—A set of copper screens, some on skeleton rack with transverse pieces at left, some in solid board 
rack with grooves at right, one on edge at bottom of left-hand rack, and one, seen partly from above, on the 
able in the center; soild copper pan on edge at right. (From Hall, 1917.) 
down the sink in which the rack is set. 
The less unpleasant material, with 
whatever parasites may be present, 
remains on the screens and is trans¬ 
ferred to shallow glass dishes either by 
washing or by immersion in water in 
the dishes and tipping to remove all or 
part of the contents at a time. In 
either case the screens are jhaced in 
sedimenting and washing repeatedly to 
remove the supernatant discolored 
fluid and flocculent material. The 
parasites are washed out of the ingesta, 
making their recognition and collection 
easier and more certain. The malodor¬ 
ous material is removed much more 
promptly and the entire process of 
examination is much pleasanter. 
