C. Warburton 271 
stronger in the <$, of a quadrangular, chitinous, granular, yellowish “plastron,” 
presenting in the middle of its anterior border two rudiments of stigmata; 
(3) the presence, on the notogaster of the rf, of two chitinous, granular, 
yellowish, circular, symmetrical plates between the four rows of spinules. 
Continuing his studies on Sarcoptes collected by himself from the giraffe, 
gazelle, wolf etc., and on specimens furnished him by Gervais from the llama, 
moufflon, cabiai etc., he found in them precisely the same details of structure. 
Finally, on examining specimens taken from patients at the hospital of 
St Louis he was again able to recognise the characteristics he had thought 
peculiar to his new species on the horse, but so indistinct and colourless that 
they were not noticeable until especially looked for. His conclusion is that 
the German authors 5 have depended on habitat and insignificant characters 
in founding a large number of species, while there is in reality only one species 
S. scabiei , with a certain number of varieties. He finally remarks.' “The 
different varieties are characterised by a difference of activity in their poisonous 
buccal liquid. I have just recently placed on the horse the Sarcoptes taken 
from the wolf, and they gave rise to colonies which in ten days invaded the 
whole surface of the pachyderm, giving rise to a scabies much more severe 
than that caused by its own proper Sarcoptes ! ” 
This passage, be it remarked, long antedated the works cited above in 
which authors of such undoubted authority as Kramer, Canestrini and Berlese 
give extensive lists of distinct species of Sarcoptes. 
The plan -which seems best adapted to our purpose is to give in the first 
place a full account of the Sarcoptes of man as far as it is known, indicating 
differences of opinion where they exist, and then to deal briefly with the forms 
which affect other animals. Many of the latter are occasionally to be found 
on man, but it is usually easy to trace the circumstances of contagion from 
definite mangy animals, whereas the disease of scabies which exists year after 
year in the poorer and more crowded parts of our cities is held to be due to 
the particular form whether species, variety or race—known as Sarcoptes 
scabiei De Geer. Delafond and Bourguignon, indeed, state their opinion 
(1862, p. 102) that if human scabies depended entirely on successive genera¬ 
tions from man to man it would have been stamped out long ago, because so 
easy to treat, but that it is reinforced from domestic animals; and again 
(p. 142) they say Man seems rather to have the Sarcoptes and the Scabies 
of animals than a Sarcoptes and a Scabies peculiar to the human species.” . 
But whatever truth there may be in this, it is certainly the case that one 
form of Sarcoptes , in default of treatment, is perfectly at home on mankind, 
and can maintain its ground for an indefinite period without any reinforce¬ 
ment from other sources, and has come to be regarded as par excellence the 
Sarcoptes of man. 
Incidentally it may be remarked that the same two investigators (D. and B.) 
insist on a remarkable difference between man and other animals, as the 
hosts of Sarcoptes. In other animals, they say, a certain “predisposition” is 
Parasitology xn i q 
