July 15, 1904.] 



SCIENCE. 



87 



to the writer to state that the article in ques- 

 tion was written last January, before the final 

 results of Professors Oliver and Scott had 

 reached me, and that the footnotes which 

 called attention to the later discoveries were 

 added in April, when I read the proof. 



With regard to the statement in the opening- 

 paragraph that the term Cycadofilicales was 

 ■destined to become a permanent acquisition 

 to taxonomy, I had in mind rather the idea 

 that botanists would henceforward be unable 

 to dispute the existence of paleozoic plants 

 intermediate between the Pteridophyta and! 

 the Gymnosperms, rather than the question of 

 terminology, and hence did not notice this 

 slip of expression in a paper which further 

 on mentions a new and vastly more appro- 

 priate name for the group in question. 



Edward W. Berry. 



Passaic, N. J. 



SPECIAL ARTICLES. 

 EVOLUTION AND PHYSICS. 



Eminent British biologists have recently 

 visited severe criticisms* upon Lord Kelvin 

 ior giving voice to the opinion that evolution 

 lies beyond the borders of physics and chem- 

 istry. The zeal with which they have hastened 

 to the defense of current mechanical hypoth- 

 eses of evolution apparently causes them to 

 forget that it is exactly these physical con- 

 ceptions with which Lord Kelvin may be sup- 

 posed to be qualified to deal. And when Lord 

 Kelvin admits that the ' forces,' ' principles,' 

 ' energies ' or other abstractions in use among 

 physicists are not adequate for even a formal 

 explanation of such biological phenomena as 

 evolution, he states what is well-nigh axio- 

 matic to some, and reaches a point of view ap- 

 preciated by rapidly increasing numbers of 

 hiologists.f 



The idea that there are biological phenom- 

 ena essentially different from those of physics 

 and chemistry has nothing to do with the 

 theory of ' vital force ' of half a century ago. 

 It does not overlook the vast amount of physics 



* Science, N. S., XVIII., 138, July 31, 1903. 



t See, for example, ' A Text-book of Botany,' by 

 Strasburger, Schenck, Noll and Schimper, p. 158, 

 liondon, 1903. 



and chemistry already found in plants and 

 animals, nor the probability that multitudes 

 of similar facts remain to be discovered. To 

 argue, however, from the progress of knowl- 

 edge in these directions that all the phenomena 

 of organic existence are to be explained in 

 current physical terms is to imitate the balloon- 

 ist who reasoned that he would be able to see 

 all the way around the earth if he could only 

 go high enough. 



It is entirely possible, of course, to range 

 organic evolution under chemistry or physics, 

 but at present it seems not to assort well with 

 the other phenomena treated in these sciences. 

 The difference appears to be, furthermore, not 

 merely one of degree, but of kind, so that it 

 may well be asked whether it is not more scien- 

 tific for Lord Kelvin to recognize and admit 

 such a distinction, even though it may prove 

 ultimately to have rested on a present limita- 

 tion of knowledge, than for his critics to in- 

 sist on the identity of phenomena between 

 which no indication of relationship has been 

 shown. At least we must expect that the un- 

 prejudiced layman will think it quite as pos- 

 sible that the biologists have been indulging 

 in bad physics as that Lord Kelvin is totally 

 in error with regard to the role of physical 

 forces in biology. The outsider might even 

 wonder why the eminent specialists from the 

 two branches of knowledge are not organized 

 as a joint committee to consider whether their 

 fundamental conceptions are the same or not, 

 instead of wasting time in mutual recrimina- 

 tions of ignorance. In the scientific world, 

 such charges can not, of course, go amiss, but 

 conscious ignorance is better than unsupported 

 assertion. 



Whether the formation of crystals should be 

 called fortuitous or not is another question of 

 words; it will hardly be insisted that it is a 

 completely fortuitous ' concourse of atoms ' 

 which makes crystals of regular form from a 

 solution stirred up in a beaker; to cover our 

 ignorance we ascribe to some substances a 

 special property named crystallization. If 

 protoplasm could be obtained from a similar 

 dissolved mixture of its ingredients, this would 

 be ascribed by parity of ignorance and logic 

 to ' plasmatization ' or whatever such a prop- 



