THE ANIMAL KINGDOM. 13 



; CHAPTEE I. 



MICROSCOPIC ANIMALCULES. 



The animalcules wliicli compose the microscoj)ic world 

 have for a long time been known by the name of 

 Infusoria, but the term ought to be abandoned, as many 

 of these creatures do not live in infusions, but, on the 

 contrary, inhabit the sea and fresh -water. It would 

 therefore be better to substitute the names Microzoa and 

 Protozoa;^ the former meaning little animals, the latter 

 the obscure beginnings of animal organization. 



For a long time the anatomy of these invisible beings 

 appeared a perfect mystery, and men despaired of ever 

 comprehending it. Baron Gleichen, having steeped 

 carmine in water containing some of these animalcules, 

 was quite astonished to see them fill themselves with 

 colouring matter. But this important fact passed un- 

 noticed. BufFon and Lamarck still continued to look 

 upon them as simple little masses of animated gelatine. 



A French naturalist, Dujardin, reared up a complete 

 theory on these data. According to him the tissue of 

 the animalcule represents a sort of spongy woof, capable 

 of hoUoAving itself out into accidental cavities, which 

 admit food and expel it by means of an outlet which opens 

 for this purpose in the surface of the body. A strange 

 hypothesis, according to which the microzoon hollows out 



1 Names derived from the Greek words /j.iKpin fuioi', little animal, aud irpuTov 

 ^dov, first animal. 



