Recent Researches on the Irifusoria. 289 



generation. In regard to the infusory animals, in particular, 

 though it was known that when once existing they could propa- 

 gate their species by ova, or by the separation of the parent into 

 two or more new individuals, yet their appearance in infusions of 

 animal and vegetable substances, so circumstanced that the pre- 

 sence of parent animals or ova could with difficulty be conceived, 

 has induced many eminent physiologists to have recourse to the 

 hypothesis of spontaneous generation to account for their origin in 

 such circumstances. It will be seen as we proceed, how far Pro- 

 fessor Ehrenberg's observations tend to confirm or to invalidate 

 this theory. According to another general view of the constitutioii 

 of organized beings, it is maintained that the material particles 

 of which every plant or animal consists, are themselves efndowed 

 with an inherent vitality possessed by them independently of the 

 life of the individual plant or animal of which they forin part. 

 Accordingly when a plant or animal dies, its constituent particles 

 still retain their vitality, and may be employed again in the for- 

 mation of new organized bodies, which can be formed only from 

 such organic particles. There are, therefore, two sorts of matter 

 in the universe, organic and inorganic ; and organic matter may 

 exist in two states, either as forming a part of individual orga- 

 nized bodies or not, in both of which states it retains its vitality, 

 though in the latter state this property is possessed only in its 

 lowest degree or most simple condition, being the property of 

 life in general without the special modifications which it exhibits 

 in individual organized bodies. By the partizans of this theory, 

 the simplest forms of infusory animalcules, or monads as they 

 are termed, were regarded as nothing more than mere organic 

 particles or molecules, which being separated from one another, 

 were impressed with movements and exhibited other phenomena 

 indicative of their inherent vitality. Hence they were some- 

 times named simple vital bodies, in contradistinction to animals 

 and plants which were conceived to be formed by the aggregation 

 of them in a number and manner depending on the size and per- 

 fection of the individual which they constituted. This is nearly 

 what is meant by the theory of an universally diffused vital mat- 

 ter, or of living organic molecules. 



Without meaning to combat this theory, it must be admitted 

 that Professor Ehrenberg's observations have overthrown one 



VOL. XV. NO. XXX.— OCTOBER 1833. T 



