OTHER ITCH-MITES. 79 
distinct species of mites belonging to three different genera. 
As but very few of these parasites cause real injury to 
their hosts excepting if they should become very numerous, 
it is not necessary to describe them in detail. In extreme 
cases they disturb, locaily, the formation of feathers, and 
may, by deranging nutrition, cause a fatal consumption. 
Proper cleanliness in poultry-houses and bird-cages will 
greatly lessen their numbers. 

Fig.44. Miteinfesting bird, 
Fig. 43. Mite infesting bird, female. Greatly enlarged. Origi- 
male. Greatly enlarged. Origina nal. 
| There are a number of other mites, belonging to different 
families, which can also, in extreme cases, cause itch-like dis- 
eases. Such mites are not usually found permanently upon 
man and domesticated animals, but only occassionally in- 
vade them. 
But it is not alone the skin of animals that is inhabited 
by mites; even the air-sacs of chickens are invaded by white 
mites large enough to be seen with the naked eye. Such para- 
sites ( Cytodites nudus Vizioli) enter the bronchiand may even 
reach the interior of air-canals in the bones. If not numer- 
ous their presence is not detected, but if favored by suitable 
conditions they increase rapidly in number and kill their 
hosts. An autopsy revealed them also in the lungs, liver, 
and kidney. Another species of mite (Symplectoptes cysticola 
Vizioli) causes an irritation in the connective tissues, form- 
ing tubercles, inside of which they may be found; they also 
