700 PHILOSOPHICAL TRANSACTIONS. [anNO 1755. 



stances, and capable of enduring a great degree of heat, without being destroyed, 

 the germs of which are sooner or later developed according to the fitness of the 

 nidus, as is the opinion of the learned and ingenious Dr. Parsons, in his treatise 

 on the analogy between the propagation of animals and that of vegetables : as by 

 entering into a discussion of these different sentiments, a large volume might 

 be written without perhaps going to the bottom of the matter. Mr. W. there- 

 fore only observes, that whichever of these opinions we embrace, thus far seems 

 to be certain, that the earlier or later appearance of microscopical animalcules, 

 is always in proportion to the degree of tendency to putrefaction in such sub- 

 stances as afford them. This is the case not only with them, but likewise with 

 maggots in meat, which every body knows are produced from the eggs of flies. 

 The two substances millepedes and cantharides, on which the above observations 

 were made, are very putrescent, and the infusions of them soon stunk abominably. 



Castor, though an animal substance, and seemingly very much exalted, 

 treated in the same manner as the above-mentioned substances, viewed by the 

 microscope every day, and kept for several months, afforded no animalcules, nor 

 seemed to have undergone the smallest change ; which confirms what the inge- 

 nious Dr. Pringle has observed, that it is antiseptic ; and adds weight to the ob- 

 servation made above, that the appearance of such animalcules denotes a tendency 

 to putrefaction. Hence Mr. W. thinks that such microscopical observations, 

 made with accuracy, might be usefully applied in the investigation of the septic and 

 antiseptic qualities of animal and vegetable substances ; since in this way the first 

 motion of putrefaction may be discovered, before it manifests itself otherwise. 



Mr. W. subjoins a few remarks concerning exaltation, which seem to deserve 

 attention. All exaltation, he observes, appears to be a certain modification of 

 the salts and oils of bodies : a proper degree of it favours growth and vegetation, 

 and sustains animal life : a greater degree of it, which he calls the putrefactive 

 exaltation, and to which all organized bodies tend more or less, decomposes all 

 such bodies, and favours the production of microscopical animalcules, or the de- 

 velopement of the ova from which they may be hatched. A still higher degree of 

 exaltation puts a stop to this process, as also to vegetation, and in certain cir- 

 cumstances even to animal life, as happens with regard to all acrid chemical pre- 

 parations, &c. whether of the animal or vegetable kingdom. 



Those who imagine that all salts and oils hurt the vegetating force of matter, 

 have fallen into a great error ; for whence can such a vegetating force proceed, 

 but from a due mixture and modification of the salts and oils with the earthy 

 principle, which every one allows to be of itself inert ? It is true indeed, that a 

 very large portion of salts or oils renders substances antiseptic, or very slow either 

 of vegetation or putrefaction, as is well known with regard to sea-salt, a large 

 quantity of which preserves substances from putrefaction ; though, as Dr. Pringle 

 observes, a smaller one rather forwards that process, as it does likewise vegeta- 



