— 124 — 
a) As external antiparasitics, 
aethereo-oleosa come especially under consideration in the treatment of 
psoriasis. In previous times this treatment was carried oiit with balsam 
of Peru or styrax, but in the course of the last decade there have 
here also been made systematic trials to test the usefulness of such 
individual substances contained in balsam of Peru, which can be pro- 
duced artificially — this being chiefly due to the constantly increasing 
price of good balsam of Peru. Of these substances, the benzyl ester of 
benzoic acid has up to now been examined most in detail. It is dis- 
solved in soaps or fatty oils in the proportion of 25 per cent, and 
applied by inunction. The modern treatment of psoriasis with the ester 
has over the old method the great advantages of neatness, purity, and 
accurate dosage, but the disadvantage that only one substance acts on 
the mites, whilst in the other a mixture of active substances is present. 
Protection against fleas and bugs is now as before afforded by 
Persian or Dalmatian insect-powder, for the manufacture of which are 
used the blossoms of various species Pyrethrum s. chrysanthemum. Its 
activity is due, in addition to other substances, also to the essential 
oil. More detailed trials on the question whether the oil alone is useful, 
are absent, but they would seem necessary, as many persons suffer from 
severe irritation of the skin after using the powder. If the oil should 
be found to be better tolerated by the human skin, and at the same 
time have an equally powerful action on the parasites, the manufacture 
of the oil would be remunerative. But if, on the other hand, the 
inflammation of the skin should be attributable to the oil, the latter 
could no doubt be removed^). The tincture which is now occassionally 
used, has a value by no means equal to that of a solution of the 
oil in alcohol. Blumea densiflora D. C, used in India instead of 
insect-powder, contains an essential oil, like the closely allied species 
Bl. lacera D. C. and Bl. balsamifera D. C. The oil of the last-named 
species is rich in borneol; those of the other two should be submitted 
to a chemical analysis, the same as that of our oil of insect-powder. 
Against head- and body-lice the peasant has for ages used aniseed 
and parsley-seed. The pure essential oils of these and similar plants, 
or the substances anethol and apiol obtained from them, are also useful 
for these purposes. For the head they are employed in the form of 
pomades and hair- oils, which need only contain one to five per cent, 
essential oil. Many practitioners prefer pomade of balsam of Peru. 
^) I am aware that E. Hirschsohn (Pharm. Ztsclir. f. Russl. 29 [1890], 209) 
found insect powder still active after having rendered it odourless by drying it tho- 
roughly at 120 degrees C. But this does not absolutely prove that the essential 
oil of this remedy is totally inactive. Moreover, I myself found an essential oil of 
insect powder of a well-known firm by no means inactive. 
