238 CRITIQUES AND ADDRESSES. [x. 



follows that Abiogenesis has taken place. The resistance 

 of living matter to heat is known to vary within con- 

 siderable 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 re-arrange themselves into living 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 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 under which matter assumes 

 the properties we call " vital " may not, some day, be 

 artificially brought together. All I feel justified 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 commencement of life, and 

 therefore I am devoid of any means of forming a definite 

 conclusion as to the conditions 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 permissible where belief is not ; and if it 



