Spontaneous Vitality of Microscopic Animals. 3 



believe, increases in bulk to the eighth or ninth generation, and then 

 produces a sexual progeny. Hence the existence of spontaneous 

 vitality is only to be expected to be found in the simplest modes of 

 animation, as the complex ones have been formed by many successive 

 reproductions. 



Experimental facts. 



III. By the experiments of Buffbn, Reaumur, Ellis, Ingenhouz, 

 and others, microscopic animals are produced in three or four days, 

 according to the warmth of the season, in the infusions of all vegetable 

 or animal matter. One or more of these gentlemen put some boiling- 

 veal broth into a phial previously heated in the fire, and sealing it up 

 hermetically or with melted wax, observed it to be replete with ani- 

 malcules in three or four days. 



These microscopic animals are believed to possess a power of 

 generating others like themselves by solitary reproduction without 

 sex ; and these gradually enlarging and improving for innumerable 

 successive generations. Mr. Ellis in Phil. Transact. V. LIX. gives 

 drawings of six kinds of animalcula infusoria, which increase by divid- 

 ing across the middle into two distinct animals. Thus in paste com- 

 posed of flour and water, which has been suffered to become acescent, 

 the animalcules called eels, vibrio anguillula, are seen in great abund- 

 ance; their motions are rapid and strong; they are viviparous, and 

 produce at intervals a numerous progeny: animals similar to these are 

 also found in vinegar; Naturalist's Miscellany by Shaw and Nodder, 

 Vol. II. These eels were probably at first as minute as other micro- 

 scopic animalcules; but by frequent, perhaps hourly reproduction, 

 have gradually become the large animals above described, possessing 

 wonderful strength and activity. 



To suppose the eggs of the former microscopic animals to float in 

 the atmosphere, and pass through the sealed glass phial, is so contrary 

 to apparent nature, as to be totally incredible ! and as the latter are 

 viviparous, it is equally absurd to suppose, that their parents float 

 universally in the atmosphere to lay their young in paste or vinegar! 



