158 MINUTE MARVELS OF NATURE 



with perfect freedom, and positively seems to revel 

 in them. Some parasites are not by any means 

 confined to one animal alone. There are catholic 

 kinds which are found in or upon man, dog, pig, cat, 

 rat, ox, &c., and always thriving. Canaries and 

 other cage-birds produce a parasite or mite which 

 often makes excursions to the persons having 

 charge of them. The sheep-tick also occasionally 

 attacks the shepherd. Others of this tribe, in 

 addition to attacking mammals, are also found on 

 birds, tortoises (Fig. 104), snakes, and lizard--. 

 Even the bullet-proof hides of the rhinoceros, 

 and the leathery skin of the hippopotamus, are 

 subject to the torturing inflictions of a tick. Horny 

 skins or integuments are of no avail against the 

 depredations of parasites, whom Nature has armed 

 with complete sets of surgical instruments for the 

 express purpose of penetrating them. The great 

 whale of the deep is worried by them, in addition to 

 the suckers, barnacles, and other external troubles 

 with which his skin is sometimes so covered that 

 it can only be seen in patches. The hide-bound 

 elephant also has a special parasite with powerful 

 mouth organs expressly adapted to penetrate his 

 armour. 



Neither do parasites cease to exist when we 

 reach the lower shelves of Nature's museum of life. 

 Insects, for instance, are no more exempt than 



