as affecting Domesticated Animals. GO 



ailoptfd .1 very simple oxpoclient for the purpose, wliich lias 

 generally proved most successful. It consists of dusting the 

 skin over with common snufT, and two or three days afterwards 

 well washing the animal with soap and water, and, as soon as 

 the skin is dry, re])eatiiig the application. A second or third 

 dressing of this kind will suffice to kill all the parasites and also 

 their embryos, if adopted with due regard to the period of 

 incubation of the ova. Attention must likewise be given to 

 a restoration of the animal's health, from whatever cause it may 

 have suffered, or he will be exceedingly liable to bo again 

 attacked by these loathsome parasites. 



Acarus Folliculorum — Animalcule of the Hair Follicle. 



This parasitic animalcule belongs to the class Arachnida, and 

 represents, according to Professor Owen, " the lowest organized 

 form of the class." It has received various names both here and 

 on the continent, the chief among which are Demodcx FoUicn- 

 lorum, OwEX ; Entozoon, afterwards Steatozoon Follicnloriaii, 

 A\'iLSON ; 3Iacrogaster Flatyims, Miescher ; Acarus Follicu- 

 lorum, Simon and Siebold ; and Simonea Folliculorum, Ger- 

 VAIS, the last name being given in compliment to Dr. Simon of 

 Berlin, who discovered it, in 1842, in his investigations of the 

 disease known as Acne in man. Kiichenmeister states that it 

 was found by Henle at about the same time in the hair follicles 

 of the external ear, but that Henle in describing it mistook " the 

 tail for the head, and the feet for sucking discs composed of 

 pads." 



In 1843-4 Mr. Erasmus Wilson fully investigated the structure 

 and habits of the entozoon, which led to his ultimately giving 

 to the world the best account of it which we possess. He 

 thus prefaces his description : — " After perusing the account 

 of the Steatozoon Folliculorum, as given by its discoverer. Dr. 

 Simon, I determined to proceed to a verification oi his dis- 

 coveries, and being provided with an instrument probably 

 superior to that employed by Dr. Simon, I have succeeded in 

 making out certain points of structure that had escaped his 

 observations. I was not long in obtaining subjects; almost 

 every face I met with supplied me with abundance, and the 

 difficulty seems to be, not to find the creature, but to find any 

 individual, with the exception, according to Dr. Simon, of newly- 

 l)orn children, in whom these animalcules do not exist." * 



In the course of his researches Mr. Wilson discovered several 

 of these parasites, seemingly identical in every respect with those 

 of man, in the secretion of the Meibomian glands of the eyelid of 



* ' Skin Disease?,' p. 728, 4th edit. 



