MESSMATES, MUTUALISTS, AND PARASITES 17 
all directions through their tissues. Other fungi attack various 
caterpillars, e.g. the silk-worm disease known as “ muscardine” is 
due to the Silk-worm Mould (a species of Cordiceps). A number 
Fig. 1071.—A Ray-Animalcule (Avachnocorys circumtexta) with yellow cells (2), much enlarged 
of skin-diseases, such as ringworm and “ barbers’ rash” are caused 
by parasitic plants of somewhat similar nature. 
But the most notable, and at the same time the smallest, of 
the endoparasitic plants which attack animals are certain kinds 
of bacteria, which may literally swarm within the 
body, and give rise to a host of diseases, such as 
relapsing fever, typhoid, leprosy, Asiatic cholera, 
tuberculosis, diphtheria, anthrax, lock-jaw, and 
bubonic plague. Some idea of the small size of _ 
bacteria will be gathered from fig. 1073, or from Coy a Nea 
statements that make some appeal to the imagi- 5% Fy Mout (@mewe 
nation. It is said, for example, that 250,000,000 
individuals of the species associated with bubonic plague could 
be crowded into the small space of a square inch. A number 
more than six times as great as the population of the United 
Kingdom at the last census. 
