ACARUS FOLLICULORUM. 17 



Third form. It has only three pairs of feet, is narrower than 

 the other forms, the transverse rings in the abdomen are wanting, 

 and the contents are paler, and less in quantity ; in other 

 respects it resembles the first form. This younger grade is cer- 

 tainly converted into a higher form by a change of skin. 



With these forms there also occurs in the follicles of the skin 

 a cordate body, which Simon regards as an empty egg-shell, and 

 Wedl as a very young animal. The latter appears to suppose that 

 this very young animal occurs already in the anterior part of the 

 belly of the mother, and that he was able to observe the develop- 

 ment of the six-legged form from this structure, its middle and 

 hinder part diminishing in breadth, and becoming elongated, 

 when oval organs and pad-like elevations (feet) grew forth. 

 Gruby states that he has found the same species of this family of 

 Acari upon the dog, after an experiment on the transference of 

 the human Acarus to that animal, and at the same time observed, 

 that in the course of two years these mites had increased so 

 enormously that they occupied every cutaneous follicle, and the 

 dog became in consequence quite naked ; statements which have 

 been already doubted justly by Simon and Wedl. Oschatz found 

 a similar Acarus in the glands of the eyelids of a sheep. It was, 

 however, broader generally, and especially in front. 



Symptomatology. Even Simon admits the possibility that this 

 animal, innocent as it is in general, may, by excessive increase, 

 become the cause of morbid beauty-spots (pimples and acne 

 pustules). Very recently Remak has narrated the case of a healthy 

 tradesman, twenty-six years old, who travelled a great deal, arid 

 had suffered for three years disfiguring acne on the chin, nose, 

 and forehead, as well as on the back. On account of a sore on 

 the glans penis, which was observed about a year after this erup- 

 tion, but soon disappeared without leaving a scar, the patient had 

 subsequently been dosed with mercury, Zittmann's decoction, cod- 

 liver oil, and many other things, without these remedies or the 

 prescribed water-cure having any influence upon the disorder. At 

 length, after long seeking, Remak found the mite, but with great 

 difficulty,, namely, by entirely removing the pustules, and dragging 

 the Simoniaii mite from their bottom, sometimes from a depth 

 of nearly a line. From this case it appears that in particular 

 cases the mite may become the true cause of pathological condi- 

 tions. 



Diagnosis. In living persons, especially if fat, as well as iii 



2 



