102 THE POPULAR SCIENCE MONTHLY. 



tions in a great number of instances, after the introduction of a limited 

 quantity of air, the genetic power of the infusions had not been de- 

 stroyed by the material conditions of the experiments. Besides, this 

 objection, which has been raised ever since the earliest controversies 

 between the heterogenists and the panspermists, has been definitely 

 answered by an experiment made by M. Pasteur ; he received in a 

 flask, exhausted and deprived of living germs by the momentary ap- 

 plication of a sufficiently high temperature, some blood at the instant 

 that it left the organism, and without allowing this liquid, which is so 

 peculiarly putrescible, to come in contact with air. By permitting air 

 deprived of germs, either by calcination or simple filtration, to enter 

 the flask, and then hermetically sealing it, he found that the blood 

 was preserved for an indefinite period intact, although it had not been 

 exposed to heat. 



M. Pasteur has also shown that air may be deprived of germs by 

 its passage through a capillary tube bent upon itself. It is, therefore, 

 sufficient, in most cases, to draw out the neck of the flask so as to form 

 a very long, narrow tube, which is bent in several directions, as, for 

 example, in Fig. 5. When the air originally contained in it has 

 been expelled, and the preexisting germs killed by prolonged boiling, 

 the flask is allowed to cool slowly. 



In closing our account of M.Pasteur's interesting memoir, in which 

 heterogenesis was driven to its last intrenchments, we must add that 

 this learned chemist endeavored to deprive his adversaries of one of 

 their principal arguments. Experiments on spontaneous generation 

 have always been conducted with vegetable or animal infusions ; it 

 was supposed by Needham, Buffbn, and Pouchet, that organisms were 

 only thus produced at the moment of expiring Nature, when the ele- 

 ments of the beings on which they are developed ai*e entering into 

 new chemical combinations, and are passing fully through the phe- 

 nomena of fermentation or putrefaction. 



In other words, albuminoid matters preserve in some degree a cer- 

 tain reserve of vitality, which would allow them to become organic 

 by contact with oxygen, when the conditions of temperature and hu- 

 midity are favorable. Starting with the idea that albuminoid sub- 

 stances are only aliments for the germs of infusoria, mucidines, or fer- 

 ments, M. Pasteur has proved directly that organic substances may 

 be replaced by those which are purely mineral or artificial, or, at 

 least, by substances on which this imaginary vegetative force cannot 

 be supposed to have any influence. 



