124 
Loa papionis n. sp. 
(2) Brumpt (1913), remarks that in stained preparations the sheath 
stains poorly and therefore often appears to be absent. However, other 
writers do not emphasize this point, and it is certain that, on occasions, the 
sheath of Ml. loa may be very prominent in stained preparations. 
(3) Manson (1912), represents Ml. loa as having the extremity of the tail 
sharply bent, while Fiilleborn denies this to be the case. I seldom noticed 
this peculiarity in larvae from the blood, but it was frequently present in 
embryos taken from the fsmale genital tract. This flexion of the tail clearly 
represents the terminal stage of the uncoiling process, and the microfilariae 
figured by Manson must be assumed to have reached the blood at a rather 
earlier stage than is usually the case. 
On the whole, it looks as though the sheath in Ml. loa represents a moult 
rather than a persistent egg membrane in a certain proportion of cases, while 
statements concerning its invariable presence must, temporarily at any rate, 
be regarded with a certain amount of scepticism. 
The buccal apparatus. The structure of the buccal apparatus—if it really 
exists—is most obscure. Manson (1912) gives the following description for 
Mf. bancrofti. “When the movements of the living microfilaria have almost 
ceased, by careful focussing it can be seen that the head end is constantly 
being covered and uncovered by a six-lipped—or hooked—and very delicate 
prepuce; moreover one can sometimes see a short fang of extreme tenuity 
based apparently on a highly retractile granule, suddenly shot out from the 
uncovered extreme cephalic end, and as suddenly retracted.Recent ob¬ 
servers seem sceptical as to the existence of these structures. Looss (1914) 
frankly puts them down as optical phenomena. Fiilleborn (1913) is doubtful 
about the existence of the prepuce and thinks the retractile appendage 
described by Manson was probably the upper edge of the sheath. 
Personal observations. In fresh preparations I not infrequently noticed 
a terminal or sub terminal spot or granule, together with an elongated, rather 
clear area behind it; this granule was often very refringent, while both it and 
the clear area were frequently visible in dead as well as in living larvae. In 
dried smears stained by the panoptic method, a central red streak or series 
of dots was sometimes present in this situation. 
In the living larva I once observed an appearance of rhythmic movement 
a short distance behind the anterior extremity, but saw no denticulations. 
From time to time a filament appeared to be shot out and retracted for a 
distance of some 20/x, while the refringent granule was a conspicuous object. 
On the following day, the movements were less energetic; on many occasions 
one filament appeared to be protruded and two retracted or vice versa; some¬ 
times two filaments seemed to be protruded and retracted, while finally, 
the rounded but empty sheath was occasionally visible in front of the anterior 
extremity. • 
My final opinion is that the prepuce and filament described by Manson do not 
exist in Ml. papionis , such appearances being mere optical illusions occasioned 
