1893.] An Extreme Case of Parasitism. 347 
says: “Several authors of modern times have reported that 
they have discovered an apterous insect, almost invisible to the 
naked eye, within the vesicles of scabies, which they have 
described under the name of acarus scabiei,” ete. The author 
does not state whether he believes this.’ 
The labors of many observers in 1834 and 1836 firmly estab- 
lished the true nature of the itch or scabies. In 1845 and 
1846 the minute anatomy of the insect was thoroughly studied 
and described.’ The mite Sarcoptes scabiei, as the cause of the 
itch, was established beyond all doubt. 
In recent medical works, I find there is little uniformity in 
regard to the systematic classification of this animal and its 
generic and specific names. The latter are variously given, 
the most popular seems to be Acarus scabiei. Frequently, all 
the different names are given. A recent treatise has it thus: 
“The acarus scabiei, sarcoptes scabiei, or sarcoptes hominis, 
commonly called the itch mite.” Authorities for names are 
never given. The accounts of the animal are often very brief 
and unsatisfactory. The size of the mites is variously given. 
According to some it is “ very minute, almost microscopic; ” 
according to others, “ the size of a pin head.” The pictures or 
figures of the mite differ greatly. In one work consulted—a 
standard text-book by the way—an entirely different mite is 
figured.’ From the great numbers of mites which I had for 
comparison, I may say, without going into invidious distinc- 
tions, that the best figures I have seen are those in Taylor's 
“Atlas of Skin Diseases.” Dr. Piffard’s atlas contains an excel- 
lent photo-micrograph of the female acarus. 
The itch mite is now universally called by entomologists 
Sarcoptes scabiei De Geer. The names Acarus scabiei and 
Sarcoptes hominis, given in many medical works should be 
dropped. Acarus and acari as synonyms for mite and mites 
are, of course, allowable. 
The best description of the mite I have seen is Hebra’s. It 
‘runs: “ Body oval, tortoise-shaped, with indentations in the 
t Reyer, “ Diseases of the Skin” (John Bell), 1845. P. 135-136. 
` 5 Hebra, “ Diseases of the Skin.” P. 187-489. 
6 Shoemaker, “ Diseases of the Skin,” 1892. P. 700. 
1 Frey, “ Microscope and Microscopical Technology,” Cutter, 1880. P. 562. 
