ADDRESS. Ixxxiii 



On the other side, the sole assertions worthy of attention are, that 

 hermetically sealed flnids, which have been exposed to great and long- 

 continued heat, have sometimes exhibited living forms of low organiza- 

 tion when they have been opened. 



The fii'st reply that suggests itself is the probability that there must 

 be some error about these experiments, because they are performed on an 

 enormous scale every day, with quite contrary results. Meat, fruits, vege- 

 tables, the very materials of the most fermentable and putresciblc infusions, 

 are preserved to the extent, I suppose I may say, of thousands of tons every 

 year, by a method which is a mere application of Spallanzani's experiment. 

 The matters to be preserved are well boiled in a tin case provided with a 

 small hole, and this hole is soldered up when all the aii' in the case has 

 been replaced by steam. By this method they may be kept for years, with- 

 out putrefying, fermenting, or getting mouldy. Now 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 meats 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 Abio- 

 genists 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 reaUy 

 trustworthy, it by no means follows that abiogenesis 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 surrounding medium. But if, in the present state of science, the al- 

 ternative 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 themselves into liviug bodies, exactly 

 such as can be demonstrated to be frequently produced in another way, I 

 cannot understand 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 futui-e. "With organic chemistry, molecular physics, and phy- 

 siology 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 under which matter assumes the properties we call " vital " may 

 not, some day, be artificially brought together. All I feel justified in affirm- 

 ing 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 commencement of Kfe, and therefore I am devoid of any means of 

 forming a definite conclusion as to the conchtious of its appearance. Belief, 

 in the scientific sense of the word, is a serious matter, 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 per- 

 missible 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 conditions, which it can no 



