PROFfiSSOH VIRCHOW AtfD EVOLUTION. 647 



checks licentiousness in speculation while the thing to 

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

 And here 1 am in the hands of the meeting, willing to end 

 but ready to go on. I have no right to intrude upon you 

 unasked the unformed notions which are floating like clouds, 

 or gathering to more solid consistency in the modern specu- 

 lative mind." 



I then notice more especially the basis of the theory. 

 "Those who hold the doctrine of evolution are by no 

 means ignorant of the uncertainty of their data, and they 

 only yield to it a provisional assent. They regard the 

 nebular hypothesis as probable; and, in the utter absence 

 of any proof of the illegality of the act, they prolong the 

 method of nature from the present into the past Here 

 the observed uniformity of nature is their only guide. 

 Having determined the elements of their curve in a world 

 of observation and experiment, they prolong that curve into 

 an antecedent world, and accept as probable the unbroken 

 sequence of development from the nebula to the present 

 time." Thus it appears that, long antecedent to the pub- 

 lication of his advice, I did exactly what Professor Virchow 

 recommends, showing myself as careful as he could be not 

 to claim for a scientific doctrine a certainty which did not 

 belong to it. 



I now pass on to the Belfast Address, and will cite at 

 once from it the passage which has given rise to the most 

 violent animadversion. " Believing as I do in the contin- 

 uity of nature, I cannot stop abruptly where our micro- 

 scopes cease to be of use. At this point the vision of the 

 mind authoritatively supplements that of the eye. By an 

 intellectual necessity I cross the boundary of the experi- 

 mental evidence, and discern in that ' matter' which we, 

 in our ignorance of its latent powers, and notwithstanding 

 our professed reverence for its Creator, have hitherto 

 covered with opprobrium, the promise and potency of all 

 terrestrial life." Without halting for a moment I go on 

 to do the precise thing which Professor Virchow declares 

 to be necessary. "If you ask me," I say, <f whether there 

 exists the least evidence to prove that any form of life can 

 be developed out of matter independently of antecedent 

 life, my reply is that evidence considered perfectly con- 

 clusive by many has been adduced, and that were we to 

 follow a common example, and accept testimony because 



