1 7 8 
may be of interest to any who contemplate working on similar lines 
to give the method employed. 
i he procedure followed was similar to that adopted in the 
extract of cantharidin from Spanish Fly. About 500 mosquitos, 
consisting of various species of Culicines and Anophelines (chiefly 
the former) were collected in Nyasaland (Upper Shire River. The 
weight of these, after drying at uo°C., was 0-478 gr. The dried 
mass thus obtained was ground in an agate mortar, and mixed with 
one-third of its weight of magnesia. Water was then added, and 
the mixture evaporated to dryness in a porcelain capsule on a water 
'. Dilute sulphuric acid was then added until an alkaline 
reaction was no longer obtainable, after which the water present 
was again driven off on a water bath. The dried mass thus 
obtained was next extracted with ether in a Soxhlet apparatus, 
-rom the extract thus obtained ether was removed by distillation, 
and the residue kept at ioo° C. until all water was driven off. The 
residue was then again dissolved in a small amount of ether, and 
pp le rop by diop to an area of human skin (flexor surface of 
e wrist) about 15 mm. in diameter. A small amount of solid 
material, not taken up by ether, was further extracted with 
oro orm, which was then allowed to evaporate on the same area 
No irritant effect was, however, produced, the skin remaining 
iree from redness or itching. The area to which the ether extract 
een app ied was kept undisturbed for fourteen hours without 
any change manifesting itself. 
. | 1 PP c< ' lr . therefore, that the irritant action of mosquito 
brtes cannot be attributed to the existence in these insects of any 
substance possessing a vesicant action. • 
