FILARIA IN THE PHILIPPINE ISLANDS. 129 



at night, or preferably the examination of dried specimens by the follow- 

 ing method. Four large drops are placed close together near the center 

 of the slide and they are then run together with a needle to form a thick 

 smear of the size of a small, square cover-glass. The smear is allowed to 

 dry in the air and may be examined at any time thereafter. When the 

 smear is looked over, it is first placed face downward in a shallow dish of 

 water, the ends of the slide supported upon glass rods. Within a few 

 minutes, depending upon how long the smear has been kept, the haemo- 

 globin will have become dissolved out of the smear, leaving a whitish film 

 upon the slide. This is best examined with a low-power lens while still 

 wet and without staining. The advantages of this method are that a 

 much larger amount of blood is examined than if the fresh specimen is 

 employed and that the examination may be made at any subsequent time. 

 This is very important where a large number of persons are to be examined 

 and when the specimens are taken at night. Then too, the smear can be 

 run over very rapidly and with very little strain on the vision, the filarial 

 embryo catching the eye as soon as it comes into the field. To one not 

 familiar with the appearance of the embryo in such preparations, there 

 are many objects, chiefly plant fibers, which may at a glance resemble 

 filaria, but by observing them with a higher power lens, all doubt as to 

 their nature will be removed. After having seen the filarial embryo 

 once, the examiner will have no difficulty thereafter in recognizing it 

 immediately with a low-power lens. Such preparations are of no value 

 in determining the species of the parasite, the presence or absence of a 

 sheath being about the only important point that can be determined 

 from dried specimens. Having found the parasite by this method, the 

 further study of it must be carried out with fresh specimens. 



In our investigations only one examination of one blood specimen from 

 each subject was made. On this account some slight infections with 

 filaria may have been overlooked, but it is not thought that the number 

 so missed could be very great. Among the large number of filarial cases 

 that we have seen in the last year, there were not more than a half dozen 

 in whose blood embryos could not be found in every specimen taken at 

 night. In a large proportion 20 to 40 embryos per drop could be found, 

 while in several instances the number reached well above a hundred. 



IV. DISTRIBUTION. 



The following table shows the geographical distribution of the parasite 

 in the Islands. The Provinces of Luzon and Mindanao have been 

 arranged in groups either on account of their proximity or on account of 

 tribal affiliation of the inhabitants. For the rest of the Archipelago, the 

 distribution is shown by islands. 



