BIOLOGY. 257 



been replaced by steam. By this method they may be kept for 

 years, without putrefying, fermenting, or getting mouldy. ISTow 

 this is not because oxygen is excluded, inasmuch as it is now 

 proved that free oxygen is not necessary for either fermentation 

 or putrefaction. It is not because the tins are exhausted of air, 

 for Vibriones and Bacteria live, as Pasteur has shown, without air 

 or free oxygen. It is not because the boiled meat or vegetables 

 are not putrescible or fermentable, as those who have had the 

 misfortune to be in a ship supplied with unskilfully closed tins 

 well know. What is it, therefore, but the exclusion of germs? 

 I think that abiogenists are bound to answer this question before 

 they ask us to consider new experiments of precisely the same 

 order. And in the next place, if the results of the experiments I 

 refer to are really trustworthy, it by no means follows that abio- 

 genesis has taken place. The resistance of living matter to heat 

 is known to vary within considerable limits, and to depend, to 

 some extent, upon the chemical and physical qualities of the sur- 

 rounding medium. But if, in the present state of science, the 

 alternative is offered us, either germs can stand a greater heat 

 than has been supposed, or the molecules of dead matter, for no 

 valid or intelligible reason that is assigned, are able to rearrange 



dj ^j * ^5 



themselves into living bodies, exactly such as can be demonstra- 

 ted to be frequently produced in another way, I cannot under- 

 stand how choice can be, even for a moment, doubtful. But 

 though I cannot express this conviction of mine too strongly, I 

 must carefully guard myself against the supposition that I intend 

 to suggest that no such thing as abiogenesis ever has taken place 

 in the past, or ever will take place in the future. With organic 

 chemistry, molecular physics, and physiology yet in their infancy, 

 and every day making prodigious strides, I think it would be the 

 height of presumption for any man to say that the conditions un- 

 der which matter assumes the properties we call 'vital' may 

 not, some day, be artificially brought together. All I feel justi- 

 fied in affirming is, that I see no reason for believing that 

 the feat has been performed yet. And, looking back through 

 the prodigious vista of the past, I find no record of the com- 

 mencement of life, and therefore I am devoid of any means 

 of forming a definite conclusion as to the conditions of its appear- 

 ance. Belief, in the scientific sense of the word, is a serious mut- 

 ter, and needs strong foundations. To say, therefore, in the 

 admitted absence of evidence, that I have any belief as to the 

 mode in which the existing forms of life have originated, would 

 be using words in a wrong sense. But expectation is permissible 

 where belief is not ; and if it were given me to look beyond the 

 abyss of geologically recorded time to the still more remote period 

 when the earth was passing through physical and chemical condi- 

 tions, which it can no more see again than a man can recall his 

 infancy, I should expect to be a witness of the evolution of living 

 protoplasm from not living matter. I should expect to see it 

 appear under forms of great simplicity, endowed, like existing 

 fungi, with the power of determining the formation of new pro- 

 toplasm from such matters as ammonium carbonates, oxalates 



