MALARIA EXPEDITION TO NIGERIA 
45 
as it is generally called, although closely applied to the body, is considerably longer 
than the worm it encloses, so that that part of the sack which for the time being is 
not occupied is collapsed, and trails alter the head or tail or both, as the case may be. 
It can be seen also that about the posterior part of the middle third ot the parasite 
there is what appears to be an irregular aggregation of granular matter which, by 
suitable staining, can be shown to be a viscous or some sort. This organ runs for 
some distance along the axis of the worm. Further, if higher power be used, a 
closely set, very delicate transverse striation can be detected in the musculo-cutaneous 
layer throughout the entire length of the animal. Besides this it carefully looked for 
at a point about one-fifth of the entire length of the organism backwards from the 
head end, a shining triangular V-shaped patch is always visible. What may be this 
V-spot is brought out by very light staining with dilute logwood. The dye brings 
out yet another spot, similar to the preceding, though very much smaller ; this 
second spot is situated a short distance from the end of the tail. The former I have 
designated the V-spot ; the latter, the " tail spot." . . . Staining with logwood also 
shows that the body of the little animal is principally composed of a column of closely 
packed, exceedingly minute cells enclosed in the transversely striated musculo, 
cutaneous cylinder ; at all events, many nuclei are thereby rendered visible. Dr. 
Low has recently pointed out to me that the break seen in all stained specimens in 
the central column of nuclei occurs at a point slightly posterior to the anterior V-spot. 
This break can only be recognized in stained specimens. When the movements of 
the living filaria have almost ceased, by careful focussing it can be seen that the head 
end is constantly being covered and uncovered by a six-tipped or hooked and very 
delicate prepuce ; and, moreover, one can sometimes see a short fang of extreme 
tenuity suddenly shot out from the uncovered extreme cephalic end and as suddenly 
retracted.' 
In the above description in all its details, our observations of the embryos 
occurring in cases in Nigeria completely agree ; but we think that the move- 
ments of the embryos in fresh microscopical preparations previous to the stage 
at which the anterior tip of the ' sheath ' of the worm appears to become attached 
to the glass, have been overlooked. If preparations be made and examined 
directly, it will be seen that the embryos, for a short period only, exhibit a rapidly 
progressive movement across the field — so rapid at first that they can only with some 
difficulty be traced. This movement quickly ceases, the sheath of the embryo 
apparently becoming attached by its tip as described. 
In stained specimens in our collection we have been able to distinguish the 
following spots, and their positions are indicated in a manner similar to that already 
used in describing the embryos of avian filariae — namely in percentages of the total 
length from the anterior end. The measurements have been made on a number of 
embryos, the percentages having been found to agree very closely in each. The 
average total length in stained specimens was 180-2 m- 
