THE GROWTH OF SCIENCE IN THE NINETEENTH CENTURY. 173 



the coiitinuecl diti'eretitiation of a priinitively .simple iiuiteriiil. It was 

 al.so made elear that the suceessive chang-es which the embryo under- 

 oocs ill its prog-ress from the ovum to maturity are the expression of 

 morphologic laws, that the progress is one from the general to the 

 special, and that the shifting scenes of embryonic life are hints and 

 tokens of lives lived by ancestors in times long past. 



If we wish to measure how far off in biologic thought the end of the 

 last century stands, not only from the end, but even from the middle 

 of this one, we may imagine Darwin striving to write the Origin of 

 Species in 1790. We may fancy him being told by philosophers 

 explaining how one group of living beings differed from another group 

 because all its members and all their ancestors came into existence at 

 one stroke when the first-born progenitor of the race, within which all 

 the rest were folded up, stood forth as the result of a creative act. 

 We may fancy him listening to a debate between the philosopher who 

 nraintained that all the fossils strewn in the earth were the remains of 

 animals or plants churned up in the turmoil of a violent universal 

 flood, and dropped in their places as the waters went awa}', and him 

 who argued that such were notreall}' the " spoils of living creatures," 

 ])ut the products of some plaj^ful plastic power which out of the super- 

 abundance of its energy fashioned here and there the lifeless earth into 

 forms which imitated, but only imitated, those of living things. Could 

 he tunid such surroundings, by any flight of genius have beat his way 

 to the conception for which his name will ever be known? 



Here I may well turn away from the past. It is not ui}" purpose, 

 nor, as I have said, am I fitted, nor is this perhaps the place, to tell 

 even in outline the tale of the work of science in the nineteenth cen- 

 tury. I am content to have pointed out that the two great sciences of 

 chemistry and geology took their l)irth, or at least began to stand alone, 

 at the close of the last centur}-, and have grown to be what we know 

 them now within al)out a hundred 3'ears, and that the study of living 

 beings has within the same time been so transformed as to be to-day 

 something wholly difl'erent from what it was in 1799. And, indeed, 

 to say more w^ould be to repeat almost the same story about other 

 things. If our present knowledge of electricity is essentially the child 

 of the nineteenth centur}' , so also is our present knowledge of many 

 other branches of physics. And those most ancient forms of exact 

 knowledge, the knowledge of numlwrs and of the heavens, whose 

 beginning is lost in the remote past, have, with all other kinds of 

 natural knowledge, moved onward during the whole of the hundred 

 years with a speed which is ever increasing. I have said, I trust, 

 enough to justify the statement that in respect to natural knowledge a 

 great gulf lies between 1799 and 1899. That gulf, moreover, is a two- 

 fold one: Not only has natural knowledge l)een increased, but men 

 have run to and fro spreading it as they go. Not onh^ have tlie few 



