400 FEAGMENTS OF SCIENCE. 



tion, I have had the honour of addressing audiences in 

 Liverpool, Belfast, and Birmingham ; and in these 

 addresses the theory of evolution, and the connected 

 doctrine of spontaneous generation, have heen more 

 or less touched upon. Let us now examine whether 

 in my references I have departed from the views of 

 Virchow or not. 



In the Liverpool discourse, after speaking of the 

 theory of evolution when applied to the primitive con- 

 dition of matter, as belonging to c the dim twilight of 

 conjecture,' and affirming that 'the certainty of experi- 

 mental enquiry is here shut out,' I sketch the nehular 

 theory as enunciated by Kant and Laplace, and after- 

 wards proceed thus : 'Accepting some such view of the 

 construction of our system as probable, a desire imme- 

 diately arises to connect the present life of our planet 

 with the past. We wish to know something of our 

 remotest ancestry. On its first detachment from the 

 sun, life, as we understand it, could not have been 

 present on the earth. How, then, did it come there ? 

 The thing to be encouraged here is a reverent freedom 

 a freedom preceded by the hard discipline which 

 checks licentiousness in speculation while the thing to 

 be repressed, both in science and out of it, is dogmatism. 

 And here I am in the hands of the meeting, willing to 

 end but ready to go on. 7 have no right to intrude 

 upon you una&ked the unformed notions which are 

 floating like clouds, or gathering to more solid con- 

 sistency in the modern speculative mind. 9 



I then notice more especially the basis of the theory. 

 ' Those who hold the doctrine of evolution are by no 

 mtans ignorant of the uncertainty of their data, and 

 they only yield to it a provisional assent. They re- 

 gard the nebular hypothesis as probable ; and, in the 

 utter absence of any proof of the illegality of the 



