1870.] BRITISH ASSOCIATION. 333 



organic cbemistry, molecular physics, and physiology yet in their 

 infancy, a:id every day making prodigious strides, I think it would 

 be the height of presumption for any man to say that the condi- 

 tions 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 ori- 

 ginated, would be using words in a wrong sense. But expectation 

 is permissible where belief is not ; and if it were given to 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 more see 

 again than a man may 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 deter- 

 mining the formation of new protoplasm from such matters as 

 ammonium carbonates, oxalates and tartrates, alkaline and earthy 

 phosphates, and water, without the aid of light. That is the 

 expectation to which analogical reasoning leads me ; but I beo- 

 you once more to recollect that I have no right to call my ooinion 

 anything but an act of philosophical faith. 



So much for the history of the progress of Kedi's great doctrine 

 of Biogenesis, which appears to me, with the limitations I have 

 expressed, to be victorious along the whole line at the present 

 day. 



As regards the second problem offered to us by Eedi, whether 

 Xenogenesis obtains, side by side with Homogenesis ; whether 

 that is, there exist not only the ordinary living things, giving- rise 

 to offspring which run through the same cycle as themselves, but 

 also others, producing offspring which are of a totally different 

 character from themselves, the researches of two centuries have 

 led to a different result. That the grubs found in galls are no 

 product of the plants on which the galls grow, but are the result of 



