606 PHILOSOPHICAL TRANSACTIONS. [aNNO 1748. 



or plants were for this reason improper, because they might have been judged to 

 have been previously adhering to these plants or seeds: he neglected no pre- 

 caution, even as far as to heat violently in hot ashes the body of the phial; that 

 if any thing existed, even in that little portion of air which filled up the neck, 

 it might be destroyed, and lose its productive faculty. Nothing therefore could 

 answer his purpose of excluding every objection better than hot roast meat gravy 

 secured in this manner, and exposed for some days to the summer heat: and as 

 he was determined not to open it, till he might reasonably conclude, whether, 

 by its own principles, it was productive of any thing, he allowed sufficient time 

 for that purpose to this pure unmixed quintessence, if it may be so called, of 

 an animal body. From this time he took corruption entirely in a philosophical 

 sense, for the rising of a dead substance, by a new kind of vegetation, into 

 life : and no axiom, how much soever it may have been exploded, is more true 

 than that of the ancients, corruptio unius est generatio alterius; though they 

 drew it from false principles, and so established it as to render generation equi- 

 vocal, and never penetrated sufficiently into nature by microscopes, to discover 

 this class of beings, that are neither generated nor generate in the common way, 

 yet furnish a key to lead to the generation of all others. His phial swarmed 

 with life, and microscopical animals of most dimensions, from some of the 

 largest ever seen, to some of the least. The very first drop he used on opening 

 it, yielded multitudes perfectly formed, animated, and spontaneous in all their 

 motions: and thus was he obliged to abandon not only the notion preconceived 

 of a distinction to be made in this class of animals, between those that appeared 

 imder a sensible angle in the microscope, and the atomical ones; but even that 

 hypothesis also which he had advanced as probable, in the little essay published 

 in 1745, that spermatic animals were no more than multitudes of such machines 

 as those of the calamary; for now it was plain of what kind they were, and 

 whence they derived their origin. 



He would not then trouble the reader with a detail of observations on 3 or 4 

 scores of different infusions of animal and vegetable substances, posterior to 

 these on mutton gravy ; all which constantly gave him the same phenomena, 

 with little variation, and were uniform in their general result : these might better 

 appear at length on some other occasion; let it suffice for the present to take 

 notice, that the phials, closed or not closed, the water previously boiled or not 

 boiled, the infusions permitted to teem, and then placed on hot ashes to de- 

 stroy their productions, or proceedings in their vegetation without intermission, 

 appeared to be so nearly the same, that, after a little time, he neglected every 

 precaution of this kind, as plainly unnecessary. He would take no notice yet 

 of their manner of being generated and generating; in relating these discoveries, , 

 as he believed he should be more intelligible, if he followed the order of time. 



