16, 1 Haughwout and Horrilleno: Intestinal Parasites 9 
We used the ether-concentration method of Cropper and Row 
in preference to any of the excellent flotation methods, because 
our experience bears out that of Cropper and Row that solutions 
of high concentration have a tendency to distort protozoan 
cysts, thereby rendering their identification more difficult. The 
flotation method is unquestionably an excellent and convenient 
one when the search is restricted to ova of helminths. 
In no case did we detect cysts of protozoa on concentration 
that we failed to find in the course of examining the slides of 
fresh or stained material. 
Our method did not differ essentially from that of Cropper 
and Row, except that we emulsified the feces in a test tube. 
The lumps of feces were transferred to the tube with a small 
amount of saline solution and then thoroughly broken down 
and emulsified by stirring with a glass rod. Saline solution was 
gradually added and the stirring continued until there was 
complete emulsification of the mass. The maximum amount of 
solution was then added and the tube thoroughly shaken for 
several minutes. The entire sediment left in the centrifuge 
tube was examined microscopically. 
This method, of course, necessitated careful attention to the 
cleansing of all utensils. This was not entrusted to the labor- 
atory attendant, but was performed by one of us. All the ap- 
paratus was thoroughly washed off in a strong stream of running 
water, carried into a jar of strong lysol solution, and repeatedly 
scrubbed out with a stiff test-tube brush, the lysol being changed 
several times, after which the apparatus was again subjected 
to running water and carefully dried with absorbent cotton 
rolled around a small stick of wood. 
Notwithstanding our figures are not widely different from 
those recorded by careful workers in the Philippines in the past, . 
we would, had we not employed concentration methods, have 
missed 32.6 per cent of the helminthal infections. Table 5 
shows the infections picked up on concentration that were 
missed on direct examination. 
TaBLE 5.—Infections detected only on concentration. 
Trichuris 31 
Hookworm 8 
Ascaris 5 
Oxyuris 1 
Total 45 
Furthermore, two cases (Nos. 20 and 34) were missed in the 
laboratory, but later proved to be infested with Ascaris through 
