February 6, 1908] 



NATURE 



319 



The Inheritance of " Acquired " Characters. 



I HAVE looked with much interest for some reply from 

 your reviewer to the queries put to him in the letter of 

 Mr. Spiccr (January 16, p. 247). 



But while he does not attempt to enligjhten us, Mr. 

 Arehdall Rcid, one of the principal exponents of " the 

 infant science of heredity," seeks to show in your columns 

 of January 30 (p. 293) that there is no real basis for this 

 controversy — that Weismann and Herbert Spencer, and all 

 others who have dealt with the question, are alike in error 

 in supposing that there is any real difficulty to be solved. 



.Mr. Reid seeks to establish his position in this way. 

 He objects to the distinction commonly drawn between 

 " innate" and "acquired" characters; he says these arc 

 inaccurate distinctions, and that they have given rise to a 

 long drawn but " futile controversy." He holds the 

 peculiar view that " in man the main difference between 

 the infant and the adult is due to the use acquirements 

 made by the latter during development." Thus, he 

 says : — " Nutriment supplies the material but noi the 

 stimulus, for all growth. Up to birth, the human being, 

 for example, develops wholly, or almost wholly, under this 

 stimulus. Subsequently some of his structures continue 

 to develop under it, for instance, his hair, teeth, external 

 ears, and organs of generation, which grow whether or 

 not they be used. But most of his structures now develop 

 mainly, if not solely, under the stimulus of use, for 

 example, his voluntary muscles, limbs, heart, and brain." 

 But surely the fact that use occurs during the development 

 (and therefore, of course, has some share in promoting 

 the growthj of some parts of the human body must not 

 blind us to the probable fact that the post-natal growth 

 is essentially due to the same inherent causes as pre-natal 

 growth. That being so, is it not absurdly inaccurate to 

 say that " in man the main difference between the infant 

 and the adult is due to use acquirements"? 



Then, again, Mr. .Archdall Reid seems to assume (in the 

 face of multitudinous difficulties) that the germs of all 

 human beings are potentially alike. He says " innate 

 characters arise inevitably as the child develops, whereas 

 some acquirements are more or less rare. But this is only 

 because the stimulus of nutriment is inevitably received, 

 whereas the stimulus of a particular use or injury may 

 not be received. If, however, the latter be received, tlie 

 acquirement arises just as inevitably as the innate 

 iharacters." ' 



This may, and probably does, hold good for the result 

 of injury and the production of scar tissue, but surely 

 not in regard to the effects of use. No amount of use 

 exercise could make a colour-blind man a good colourist, 

 or enable many persons having, as it is commonly said, 

 " no ear for music " to be good musicians. Thus in some 

 persons what in the majority should be innate qualities 

 iire found to be wanting (owing to defects in organisation), 

 while in other persons, wholly independent of any com- 

 mensurate amount of use exercise, powers like those 

 possessed by a Turner or a Watts, by a Mozart or a 

 Beethoven, or such powders in the direction of mental 

 arithmetic as were found in Bidder, Inaudi, and others. 

 One person has highly developed auditory centres and 

 cerebral regions in association therewith, another has a 

 poor development of the same parts, and the same thing 

 holds good for the visual centres and their associated 

 cerebral mechanisms. Some of those having highly 

 developed auditory centres may prove to have unusual 

 musical abilities, while other persons, like Inaudi, may 

 have marvellous powers in dealing with figures. 



It is, in fact, notorious that the stimulus of nutriment 

 and the stimulus of use being present, the results in the 

 way of acquirement will vary ad infinitum in accordance 

 with innate differences in individual germs. Yet it is upon 

 the basis of such views as I have quoted that Mr. Reid 

 strives to show that the controversy as to the alleged 

 ■" transmission " of acquired characters is due to a mis- 

 understanding. " Had the true nature of the distinction 

 between innate and acquired characters been realised," he 

 says, " had it been realised that the difference is one of 

 stimuli, not of innateness or inheritability, and that 

 acquirements are just as much products of evolution as 



t No it.ilic^ her; in origina'. 



NO. 1997, VOL. yy] 



innate characters, it is impossible that the controversy 

 as to the alleged ' transmission ' of the former could have 

 endured so long as it did." 



I venture to think that many will not be satisfied with 

 Mr. Archdall Reid's doctrines, and will still consider that 

 the controversy is not closed, as he seems to suppose, but 

 that there is a real problem open to discussion ; and 

 certainly those who believe that the effects of use and 

 disuse may be inherited will not find anything in Mr. 

 Reid's letter to show that they are wrong. 



In your pages in 1905 (June 15, p. 152) there was a 

 brief communication on this subject from Mr. Woods 

 Smythe which I take to be of considerable importance. 

 He says : — '■' Lately I heard a missionary at a May meet- 

 ing tell of the marvellous facility with which Chinese 

 children memorise whole books of the Bible; the four 

 Gospels, and sometimes the Acts also, being an easy feat 

 for children of ten or twelve years. Having carefully 

 sought information from other authorities, I find these 

 facts confirmed, and that the same applies to Mohammedan 

 children. We are aware that for ages their ancestors 

 have been compelled to memorise long portions of their 

 sacred books, and although occasionally we meet with a 

 child of any nation with a gigantic memory, that differs 

 widelv from the case of a people where it has become 

 a general characteristic." 



Facts of this kind are very difficult, if not impossible, to 

 understand except upon the supposition that use and prac- 

 tice carried on through many generations have led to the 

 begetting of germs having modified developmental 

 tendencies. 



How would Mr. Reid explain such facts? In his letter 

 he savs : — " Memory, the pow'er of learning, develops 

 under the stimulus of nutriment, but intelligence and 

 reason develop under the stimulus of use." Memory is, 

 therefore, for him one of the so-called *' innate "-characters 

 which develops independently of the stimulus of use and 

 exercise. For him, therefore, there ought to be no such 

 remarkable memorial powers as those which have been 

 referred to by Mr. Woods Smythe. 



H. CtlARLTON BaSTIAN. 



The .Athenaeum, London, February 3. 



The Nature of Rijntgen Rays. 



In Nature of January 23 (p. 270) Prof. Bragg defends 

 his neutral pair theory of X-rays, and his explanation 

 of scattering and polarisation on this theory, against a 

 criticism which I made in a recent letter (Nature, October 

 31, 1907). Though he appears to have enlarged his con- 

 ception of the possible function of the ether pulse in X-ray 

 phenomena, he contends that my one assumption is un- 

 justifiable, consequently is of no value as a critical test. 

 Prof. Bragg had assumed that a pair revolves in a plane 

 rontaining its direction of translatory motion, that when 

 incident on light atoms it is liable to be taken up only 

 by an atom revolving in the same plane, sometimes to be 

 ejected again, and that if ejected again it continues to 

 rotate in the same plane. My assumption in calculating 

 the distribution of intensity of secondary radiation was that 

 after being taken up by an atom its liability to be ejected 

 again is equal in all directions in that plane. This does 

 not appear quite so unjustifiable as, from Prof. Bragg's 

 letter, one would judge it to have been. 



It is evident, however, that this assumption is not a 

 necessary part of the argument against the neutral pair 

 theory, though it appeared, and still appears, to me to be 

 the nearest approximation one can make to the probable 

 behaviour of a pair, if we accept Prof. Bragg's previous 

 assumptions. 



But to make calculation possible in place of such a 

 definite distribution we may assume any one of a score of 

 others, as Prof. Bragg does not suggest one. .Still, experi- 

 ments supply what appears to me to be absolutely con- 

 clusive evidence in favour of the ether pulse theory. For, 

 after measuring the intensity of secondary radiation pro- 

 ceeding in a direction perpendicular to that of propagation 

 of the primary beam from a substance of low atomic 

 weight during the transmission of " soft " X-rays (con- 

 ditions producing the most complete polarisation), I have 

 found that the intensity of radiation in a direction opposite 



