PROGRESS OF VETERINARY SCIENCE AND ART. 49 
plate, fig. 9* I must not omit to say that the specimen it 
was taken from was found on the man beneath the epidermis, 
in the substance of the skin. Like other pus acari, the 
acarus setosus had burrowed for itself cavities which were 
filled with pus ; pustules and nodules existed on the surface 
of the skin in the interspaces between the holes.* 
The sarcoptes cymtis , figs. 4 and 5, was found by Hering 
in the otorrhoea of dogs, commonly known as canker of the 
internal ear. The Sarcoptes hippopodos , fig. 8 of our plate, 
was first seen by the same observer in an inveterate case of 
canker of the foot of the horse, and subsequent investigations 
have confirmed the discovery. 
In a pathological point of view, as related to the pus acari , 
we have the entozoon folliculorum of the sebaceous follicles of 
man, horse, and dog. Dr. Simon of Berlin first saw it in 
man, hence Vogt named it “ Simonea folliculorum ."+ It is the 
Demodex folliculorum of Owen.J Mr. Erasmus Wilson first 
discovered the same parasite in animals ; he found it in the 
Meibomian secretion of some eyelids of horses ; it was identi- 
cal with that of man.§ In 1843, Mr. Topping discovered 
these same animals in pustules upon the skin of a dog- 
affected with the mange. It was supposed by him that they 
were the cause of mange, but Mr. Wilson believed the 
pustules resulted from inflammation of the follicles of the 
skin. Leblanc, in 1 849, || described the disease in which the 
entozoon folliculorum is found as one of which dogs die, in one 
or two months, in a state of the most complete marasmus. 
Mr. Simonds has kindly favoured me with some specimens 
which he obtained in 1851 from a dog suffering from ex- 
tensive eruptions on the skin. Fig. 12 of the plate re- 
presents the parasite as delineated by Wilson. This 
entozoon is not truly an acarus but forms a distinct genus 
Demodex of Owen, or Simonea of the family Simonida of Vogt. 
It represents the lowest organized form of the class 
Arachnida. 
* ‘ Uebertragung der Rindvichrau.de auf den Menschen,’ von Dr. J. L. W. 
Thudichum, in the *' Illustrirte Med. Zeitung,* Miinchen, 1852, p. 259. 
f Vogt, c Zoologische Briefe, 5 vol. i, p. 500. 
J Professor Owen says ‘ Of the generic distinction of the parasite 
there can be no doubt, and I therefore propose to call it Demodex folli- 
culorum, from dri/xog, lard, and £rj%, the name of a boring worm, indicative of 
the habitat and vermiform figure of this parasitic Arachnidan, which in- 
sinuates itself into the hair-follicles and the sebaceous glands that com- 
municate therewith.” (See Owen’s ‘ Lectures on the Invertebrate 
Animals.’) 
§ See the ‘Transactions of the Veterinary Medical Association,’ for 1844, 
p. 404. 
1| ‘Gaz. Med. de Paris,’ t. iv, No. 29, p. 572. 
xxix. 7 
