THE CHICKEN-SCAB., 63 
THE CHICKEN-SCAB. 
(Sarcoptes mutans Rob. or Anemidokoptes viviparus Fuerst.). 
This mite selects such portions of the skin as are free 
from feathers, and causes a peculiar itch upon the 
legs of the bird (fig. 35), sometimes extending to the 
head (fig. 36), where it forms discolored spots. The 
mites possibly reach the combs of chickens when the latter 
are scratching these organs, or when they peck at the itch- 
ing legs. Combs invaded by this mite show white dots and 
lines covered by minute scales, which rub off quite readily, 
below them the skin is brownish, contrasting strongly with 
the normal red color. Later the feathers 
on the head undergo a peculiar change; 
they turn whitish, lose their glossy ap- 
pearance, and stand on end. Infested 
| legs are distinguished by greyish-white 
spots or scabsof various shapes and 
sizes, and by brownish swellings in the 
skin, and in extreme cases by a greatly 
swollen and scabby appearance. Under 
these scales wesee a yellowish substance 
Pig. 34. Scab-miteofchick-in which are the numerous burrows of 
cn ged Original, > the mites. The scabs thus formed give 
the legs a very peculiar and unsightly appearance—they 
look ‘‘chalky.”’ 
All the actions of the fowls show that considerable itch- 
ing takes place, which, however, does not as a general rule 
destroy the appetite of the patients. The young and six- 
legged mites are fairly active, and one diseased fowl will 
soon scatter the infection to all other birds living in the 
same roost. 
If we investigate, by means of a microscope, a small 
piece of the scab caused by these parasites, we find in most 
of the burrows small and young mites, and in the blind end of 
the burrow large females and males. But we do not findeggsin 
such burrows, as we do in the case of other itch-mites, Prof. 
Fuerstenberg discovered that these mites produced living 
young, and therefore changed the former name of these 

