22 SPONTANEOUS GENERATION. 



" We have here a series of thirty-three experiments, prepared 

 in different ways, in which solutions of organic matter, some of 

 them previously filtered, have been boiled at the ordinary press- 

 ure of the atmosphere for a length of time, varying from 15 

 minutes to 2 hours, and exposed to air purified by heat. 



" In many instances, a solution like that in the sealed flasks, 

 and boiled for the same length of time, was exposed to the ordi- 

 nary air of the room, in an open flask. Although the same 

 forms were found in the two, they appeared much more rapidly 

 in the open than in closed vessels, and the contents of the for- 

 mer soon became putrid, while those of the others, at the time 

 of opening, were mostly not, and in a few instances only 

 slightly so. 



" We have, in addition, four experiments : namely, xxxiv., 

 xxxv., xxxvi., xxxvii., made under increased pressure, and sealed 

 by the third method ; xxxiv. and xxxvi. were boiled 5' and 15' 

 respectively, under two atmospheres, and xxxv. and xxxvii., un- 

 der five atmospheres for 10' and 15' respectively. Evidence of 

 life, consisting of Monads and Vibrios, was found in xxxiv. 

 and xxxv., but none in the others. 



" The result of the experiments here described is, that the 

 boiled solutions of organic matter made use of, exposed only to air 

 which has passed through tubes heated to redness, or enclosed with 

 air in hermetically sealed vessels and exposed to boiling water, 

 became the seat of infusorial life. 



" The experiments which have been described throw but little 

 light on the immediate source from which the organisms in ques- 

 tion have been derived. Those who reject the doctrine of spon- 

 taneous generation in any of the forms in which it has been 

 brought forward, will ascribe them to spores contained either in 

 the air enclosed in the flask, or in the materials of the solution. 



" Those who advocate the theory of spontaneous generation, 

 on the other hand, will doubtless find, in the experiments here 

 recorded, evidence in support of their views. While they admit 

 that spores and minute eggs are disseminated through the air, 

 they assert that no spores or eggs of ann kind have been actually 



