548 MR. H. D. GELPART ON FILARIA SANGUINIS HOMINIS (nOCTURNa). 
it appears to be a blunt-beadecl worm with a sharply pointed tail, 
and its sheath is marked with transverse wrinkles. In this state it 
is extremely active, if pinched or hurt in trying to spread the 
blood more evenly, it knots itself up into a tight coil, then 
reversing itself with a spring it knots itself the reverse way, 
exactly as an earth-worm would do in similar circumstances ; but 
with all its activity it does not seem to advance through the blood, 
for notwithstanding all its struggles, it remains in just about the 
same position in the field of the microscope, its movements get 
more sluggish as time goes on. I have seen one move gently after 
about twenty-four hours from the time the blood was drawn ; but 
I suppose that the coagulation of the blood has much to do with 
this. As shown in slide No. 2, the embryo lias divested itself of 
its sheath, which you see trailing behind it like a colourless folded 
riband. In this state the external structure of its head can be 
made out ; from the blunt head projects a short proboscis, and from 
this proboscis projects a slender spicule. As explained by Dr. 
Manson, the great authority on the subject, the proboscis and 
spicule together constitute the tentative and boring apparatus of 
the embryo, by means of which it proceeds to its ultimate home in 
one of the lymphatic vessels of its human host, and Dr. Manson 
has published a diagrammatic figure in which he shows the 
proboscis as furnished with a lipped integument, which he con- 
siders acts as a kind of anchor, maintaining the ground won by 
the borer, and acting as a point cVappui for the next effort. I 
cannot distinguish any internal organs in this stage of the embryo ; 
the whole cavity of the body seems filled with a granular mass. 
The life history of this Filctria ( nocturna ) as worked out by 
Dr. Manson appears to be — starting with the embryo as seen in 
No. 1 — that the embryo in its sheath which only appears in the 
blood from sunset to sunrise (when its intermediate host the 
Mosquito is active) is taken up with the blood by the female 
Mosquito (the male having no apparatus for piercing the skin) of a 
certain species described as a small dark brown insect without 
conspicuous markings on either body or legs ; she is about of 
an inch in length, her head is small and dark, and she carries a 
proboscis I \ the length of her body — having gorged herself with 
her first and only meal, the Mosquito retires to some dark and 
secluded place where she remains inactive for four or live days 
