122 ON EQUIVOCAL GENERATION. 



** microscopic animals, exist universally in the atmosphere, and 

 " penetrate the sides of glass jars." Philosophical Magazine jot 

 May 1800. 



He further says, p. 9, "The green vegetable matter of Dr. 

 " Priestley, which is universally produced in stagnant water,. 

 " and the mucor, or mouldiness, which is seen on the surface 

 " of all putrid vegetable and animal matter, have probably 

 " no parents, but a spontaneous origin from the congress of 

 " the decomposing organic articles, and afterwards propagate 

 " themselves." 



Let us now compare this language with that of nature in my 

 experiments. On the first of July I placed in the open air 

 several vessels containing pump-water, two of them covered 

 with olive oil,, one in a phial with a ground glass stopper,, 

 one with a loose tin cover, and the rest with the surface of 

 the water exposed to the atmosphere ; and having found 

 (as may be seen in the account of my former experiments 

 on this green matter) that it was produced with the great- 

 est facility, and in the greatest abundance, when a small 

 quantity of vegetable matter, especially thin slices of raw pota- 

 toes, was put into the water, 1 put equal quantities, viz. twenty 

 grains of potatoe, into each of die larger vessels and ten into 

 each of the smaller. Into two very large decanters, the 

 mouths of which were narrow, I put fifty grains of the same, 

 one of them, having oil on its surface, and the other none. 

 At the same time having filled a large phial with the same 

 water, I inverted it in a vessel of mercury. 



In about a week the wide mouthed open vessel began to 

 have green matter, and the large decanter with the narrow 

 mouth had the same appearance in three weeks. On the first 

 of August the vessel which had a loose tin cover, coming 

 about half an inch below its edge, had a slight tinge of green, 

 and on the first of September the phial with the ground glass 

 stopper (but which, appeared by some of the water escaping, 

 not to fit exactly) began to have green matter. But none of 

 the vessels that were covered with oil, or that which had its 

 mouth inverted in mercury, had any green matter at all on the 

 12th of September; when, having waited as I thought long 

 enough, I put an end to the experiment. 



