MUSEUM OF COMPARATIVE ZOOLOGY. 15 
gives an account of the structure and mode of life of the parasite of 
the hair-follicles.* 
In 1859 appeared a valuable paper on Demodex by Leydig,t contain- 
ing descriptions of the parasite found on man, the cat, the dog, and a bat 
from Surinam (Phyllostoma). On the latter hundreds of Specimens were 
found in a pustule on the belly. He considers the forms from the 
various hosts as so mauy species. 
The most important contribution to the history of Demodex since 
1860 is a memoir by Mégnin. In this memoir are described three 
varieties from man, the cat, and the dog. 
In the above-mentioned papers Demodex has figured as a parasite of 
man, the cat, the dog, the fox, the bat, the ox, and the horse. It has 
also been reported from the Meibomian glands of the sheep.§ 
While in the human skin it is seldom found except in the face and 
is comparatively innocent, in the dog it may become widely spread over 
the body, and be the cause of a serious disease accompanied by a loss 
of the hair in the infected parts. 
Although noticed in the ox by Gros, as long ago as 1845,|| it has 
never been known, as far as I can learn, to induce any serious dermal 
disorder in that animal. Gros simply mentions it as found in the 
muffle, Its presence in such numbers as to damage the leather made 
of the infested skins must from its economic bearings awaken a fresh 
interest in this peculiar Arachnid. All the samples which I received 
had been soaked in lime in order to remove the hair, so that I cannot 
say whether the presence of the parasite causes the hair to fall off as 
happens with the dog; but at all events no crusts were formed upon 
the skin as in the mange. It is probable that the parasites would not 
have got such a hold upon the cattle unless their skins had become 
torpid by ill keeping, 
It may be useful to quote here the treatment recommended by 
Simonds for dogs afflicted with these parasites, as it will apply equally 
well to cattle : — 
* “Die in und an dem Körper des lebenden Menschen vorkommenden Parasiten," 
1855. English translation by Edwin Lankester, Vol. II. pp. 15 - 19, Pl. VIII. Figs, 14-16, 
1857. 
T “Ueber Haarsackmilben und Kratzmilben." Arch. f, Naturgeschichte, 1859, T. pp. 
338-347, Pl. XIII. Figs. 4-10. 
t “Mémoire sur le Demodex folliculorum, Owen.” Journal de l'Anatomie et de la 
Physiologie (Robin et Pouchet), 1877, pp. 97-122, PL IX. 
$ Kiichenmeister, op. cit. (Eng. trans.), IT. p. 17. Mégnin, op. cit., p. 105. 
|| The record of this has been overlooked by most of the recent writers on the subject, 
e. g. Simonds and Mégnin. 
