PARASITES OF ANIMALS. 39 
gen, is disagreeable, and it should be used, therefore, where 
there is plenty of ventilation. This is an exceedingly valua- 
ble remedy, also, for the itch of man, as well as the “ mange”’ 
of animals. The sulphuret of potassium comes in the form 
of grayish or greenish lumps, put up in tight bottles. It is 
used in photography and can usually be bought at the princi- 
pal drug stores. 
An equally useful preparation, having the same properties, 
may be easily made by taking fresh quick-lime, slacking it 
gradually with water, and forming a milky solution by the 
addition of more water, as in the preparation of white-wash. 
Into this put as much flowers of sulphur as will dissolve by 
boiling for some time. This will produce a deep yellow solu- 
tion like that of the sulphuret of potassium in odor and 
effects. It may be diluted if too strong. It contains svi- 
phuret of calcium, upon which its usefulness depends. Sul- 
phur may also be boiled in potash lye, to produce a similar 
preparation, and to this, while boiling, tobacco is sometimes 
added, but the sulphur is, no doubt, sufficient fer all practical 
purposes. Butin no case can we be certain of destroying all 
the eggs of these parasites by any wash whatever, that would 
not be dangerous to the animal. Therefore the treatment 
should be repeated two or three times, at intervals of ten or 
twelve days, in order to destroy any young that may have 
hatched in the meantime. 
The Head-louse of man (Pediculus capitis DeGéer). Fig. 30. 
This is, probably, the best known species of the genus 
Pediculus. It is still sufficiently common among persons who 
neglect personal cleanliness, though much less 
. so than it is said to have been formerly, when it 
was thought no disgrace in some parts of the 
old world, but was regarded as fashionable, 
rather than otherwise. This insect is almost 
exclusively confined to the human head. It 
attaches its eges firmly to the hair, near the 
roots. These eges are long-oval, with several 
little conical prominences at the large end, 
Figure 30.—Head-louse vi Feiculys mgapliseDeGéer), greatly magnified. 
From Packard’s Guide. 
Figure 30. 
