394 Mr. William Bate Hardij [April 6, 



of a cantilever, and we believe that human industry and the human 

 intellect will one day complete a bridge across which all may pass in 

 safety. But in the meantime there are grave signs in the scientific 

 and semi-scientific literature of the day of a growing impatience with 

 the rate of progress, which, on the one hand, insures ready and 

 uncritical acceptance of the crude attempts of an amateur biologist 

 to make living matter, and, on the other, breeds a feel)ler purpose 

 which seeks an unhealthy opiate in " vitalism " or some other " ism " 

 of like nature. 



Nearly forty years of vigorous scientific work have elapsed since 

 Huxley wrote, and it is still possible for the vitalist to assert that no 

 single vital process can be completely expressed in terms of physics 

 and chemistry, that is, of motion and of matter. The biologist is 

 reproached, for instance, Avith the undoubted fact that the power 

 which a living cell has of selecting certain chemical substances and 

 of rejecting others cannot yet be explained by, and indeed in some 

 ways seems to contradict, the known laws of molecular physics. 



To this reproach I would reply after the fashion of Socrates, and 

 with the same purpose, by a question. 



Here are two pairs of gases, one of hydrogen and oxygen, the 

 other of hydrogen and chlorine. I burn the members of each pair 

 together, and from the one pair I get water, a fluid odourless, innocu- 

 ous, and of relatively slight chemical activity, while from the other I 

 get hydrochloric acid gas, acrid, poisonous, and of the highest 

 chemical activity. Now, the molecules of those three gases have 

 certain inalienable properties, an invariable weight, a fixed capacity 

 for electricity. They perform movements the harmonic periods of 

 which are so fixed that apparent departures from them have been 

 used to detect and measure the velocity of approach of a star towards 

 the earth. I ask the chemist or molecular physicist to explain the 

 amazingly divergent properties of the compounds in terms of the 

 properties of the component gases. I ask him to do what over-hasty 

 people, forgetful of the extreme youth, the paucity in years of human 

 knowledge, ask the biologist to do with respect to living matter, and 

 tlie reply is that the question is unanswerable. 



It cannot be sufficiently insisted upon that in many regions not 

 the simplest more advance has been made towards a material explana- 

 tion of vital phenomena than towards a solution of the simple question 

 why one pair of gases should combine to form a fluid, while another 

 pair combine to form a gas. 



An unansweral)le question concerning the elements of natural 

 knowledge is a sharp reminder of our ignorance, and such a reminder 

 is needed to curb the s})iritual arrogance which in our time has 

 l)rought this greatest of all mysteries, the relation of living to non- 

 living matter, to tlie temples of vulgar credulity, and has prostituted 

 it to the puri)oses of connnon chai'latans and impostors. 



Since Huxley wrote, our knowledge of the physical basis of life 



