March 27, 19 13] 



NATURE 



85 



would expect. If we look to the animal world we 

 shall, broadly speaking, find that as we rise from 

 the lowliest to the highest organisms, there is a 

 steady decrease in the number of offspring, while at 

 the same time there is a lengthening- of the period 

 during which the offspring remain under the care of 

 the parents. In the case of the human race we find 

 that increasing civilisation brings with it a decreasing 

 birth-rate, and a lengthening period of " schooling " 

 for the children; and it is amongst the least intelli- 

 gent (which is also usually the lowest paid) section of 

 the community that the birth-rate is the highest. A 

 glance at the birth-rate of our English towns will 

 show that in those districts where there is greatest 

 poverty and congestion, there tends to be also a com- 

 parative!}' large birth-rate. 



The foregoing views would seem to be borne out 

 by the fact which Miss Elderton mentions, that Liver- 

 pool, " which is not a cotton town, and where the 

 amount of irregular and casual labour is singularly 

 large, is one of the two cases in Lancashire where 

 the birth-rate shows a rising tendency," and also by 

 her statement that "from Bradford figures have been 

 obtained showing how in homes where the mother's 

 health or habits are bad, or where the ventilation is 

 bad, there is on an average about one child more than 

 in homes where these features are good." 



To quote the words of Dr. Saleeby, "a chief factor 

 of progress has been the supersession of the quantita- 

 tive by the qualitative criterion of survival-value. The 

 principle of the fall of the birth-rate is one of the 

 great consistent facts of organic history, and may 

 be traced from the bacteria upwards, through such 

 representative invertebrates as the insects, even 

 through fishes, the first vertebrates, up to man, and 

 amongst the various nations and strata of human 

 society. The tendency of progress, in short — a tend- 

 ency coincident with the evolution of ever higher and 

 higher species — is to pass from the horrible Gargan- 

 tuan wastefulness of the older methods towards the 

 evident but yet lamentably unrealised ideal — that every 

 child born shall reach maturity. . . . All organic 

 history proves that a low birth-rate is a mark of high 

 vital level." J. Anderson. 



17 Laburnum Road, Gorton, Manchester, 

 March 5. 



The above letter contains no addition of any ascer- 

 tained jact to those cited by Miss Elderton. Miss 



! Elderton, in her lecture, brought forward a very 

 large amount of evidence to show that the net family 

 of the socially less valuable members of the working- 



t classes was larger than that of the socially more valu- 

 able members of the same classes. That within a 

 given species the individuals of inferior physique and 

 mentality have relatively greater fertility must mean 

 the degeneration of that species ; and no scientific- 

 argument can be opposed to this based upon the 

 illogically extended syllogism: "higher" species have 

 lower birth-rates ; there is a lower birth-rate in the 

 more valuable members of the artisan classes ; hence 

 this tends to convert those classes and their nation 

 into "higher" types of life. 



If we start to reason from analogy of this kind, we 

 might argue that the elephant would in the end sup- 

 plant man, or that the mastodon — for aught we can 

 say to the contrary — ought to have survived all his 

 contemporaries. It is the old fallacy of the Neo- 

 Malthusians, who have never made any real attempt 

 to grasp the race suicide involved in the survival of the 

 unfit bv reproductive selection — i.e. by their greater 



NO. 2265, VOL. gi] 



fertility, when it is unchecked by natural selection. 

 Argument from analogy, when data are available, is 

 always idle ; argument from what is known of species 

 to what must hold of individuals is still more falla- 

 cious. 



Lastly, association is not causation; a "higher" 

 individual may have fewer children, but this does not 

 demonstrate that his height (however that vague word 

 be defined) is produced by his lesser fertility, or that 

 a race with a large section of its "higher" individuals 

 practically sterile will survive in the battle of nations. 

 History shows many cases of the decline of nations 

 whose intellectually abler members were sterile. 1 

 can recall no case of a race with a very low birth- 

 rate maintaining or creating a position for itself in 

 the assembly of nations. 



I have not trespassed on your space by commenting 

 on Mr. Anderson's other statements. He was clearly 

 not present at Miss Elderton's lecture, or he would 

 have been aware that her data were all based on 

 married women, and had due reference to their ages. 

 While the actual birth-rate of wives, fifteen to forty- 

 five years of age, has fallen 30 per cent, to 50 per 

 cent., the potential birth-rate of the same wives has 

 fallen a few points, or in many districts not at all. 



Karl Pearson. 



Galton Laboratory for National Eugenics, 



Lmiversity of London, March it. 



The Radio-Elements and the Periodic Law. 



In his letter in Nature of March 20 Mr. Soddy 

 states that "granting the possibility of the existence 

 of groups of elements with identical chemical proper- 

 ties and spectra, the only known direct manner in 

 which the existence of the members of these groups 

 could be separately recognised is radio-active 

 evidence." I should like to suggest that another 

 possible method of distinguishing such elements is 

 provided bv their characteristic X-radiation. Accord- 

 ing to Rutherford, the 7-radiation emitted by a radio- 

 active element is identical with its characteristic X- 

 radiation ; is the 7-radiation of thorium D identical 

 with the characteristic X-radiation of thallium, or the 

 7-radiation of radium D with the characteristic X- 

 radiation of lead? From such experimental results 

 as I can discover after a brief search, it would appear 

 that the answer to this question is in the negative. 



It seems probable that a difference might exist be- 

 tween the characteristic X-radiations of elements 

 chemically identical, for the properties of that radia- 

 tion, like the radio-active properties, are probably de- 

 termined by the fixed electrons, forming part of the 

 permanent structure of the atom, since both sets of 

 properties are independent of chemical combination ; 

 on the other hand, the chemical properties are prob- 

 ably determined by the valency electrons which are 

 readily detached from the atom. If chemically iden- 

 tical elements have the same spectra, it would appear 

 that the spectra are also determined by the valency 

 electrons, a conclusion contrary to that involved in 

 Stark's theory of the origin of spectra. 



Norman R. Campbell. 



Leeds, March 23. 



The Occurrence of the Archiannelid, Protodrilus, on the 

 South Coast of England. 



The discovery of the presence of the Archiannelid, 

 Protodrilus, on the English coast is an interesting 

 fact inasmuch as it extends the known domain of a 

 genus of an archaic group of animals, and also adds 

 a valuable animal to our records. So far as is known 



