﻿4 ASHBURN AND CRAIG. 



this being impossible because of the closeness with which it envelops the 

 body. In very rare instances in the fresh specimen, the sheath may be 

 seen to be flattened out, having a ribbon-like appearance, but even when 

 this occurs the filaria does not enter the flattened portion projecting at 

 either extremity. 



We are not able to add anything to our previous description of the 

 anterior V spot, the central viscus, the posterior V spot or the tail of * 

 the worm as observed in the blood of man ; the same is true of the meas- 

 urements of the filaria as given by us and the morphology of the stained 

 specimen. 



Motility. — In our original description we stated that Filaria philippi- 

 nensis possessed two forms of motility, one lashing but not progressive, 

 which is most frequently observed ; .the other, a marked progressive 

 motion occurring but rarely. In our examinations of the filarise in -our 

 additional cases we have given special attention to the character of the 

 movements exhibited by them and have found that progressive motion 

 is much more common in fresh blood specimens than we at first supposed 

 to be the case. We have found that in thick blood smears progressive 

 motion occurs very frequently, if not as a rule, and we have also observed 

 it in very thin smears; when it takes place the movement is serpentine in 

 character, the head advancing through the surrounding masses of blood 

 corpuscles with considerable rapidity. In a fairly thick smear, in one 

 instance, a filaria in three minutes crossed four 18-millimeter (f-inch) 

 microscopic fields in almost a straight line : in another case^ eight 18-mil- 

 limeter (f-inch) fields were traversed in half a minute; in a blood smear 

 in which the cells were arranged in a single layer a filaria crossed a 

 18-millimeter (f-inch) field in one minute and six 4.25-millimeter ($- 

 inch) fields in three minutes. Even when a portion of the specimen was 

 reached in which the blood cells were in very small numbers, or indeed 

 absent, the filaria did not show entire loss of progressive motion, although 

 such clear spaces caused a temporary cessation ; in such instances, after a 

 few moments of twisting and turning, the head of the parasite would shoot 

 forward and the progressive motion be resumed; in this way we have 

 seen a filaria traverse four such open spaces in a specimen of blood and 

 in each instance as soon as it reached the intervening clumps of blood 

 corpuscles the progressive motion became more rapid and regular in 

 character. At times the tail end advanced but this was invariably followed 

 almost immediately by a propulsive effort of the tail which pushed the 

 head and body forward for a considerable distance, after which the head 

 continued its advance. In one specimen we observed progressive motion 

 of filarise for two hours after the blood was collected. 



It should be remembered that the movements, both lashing and progres- 

 sive, which have been described occur while the filaria is still inclosed 

 within its sheath, progressive motion being unimpeded by the latter. 



