December 28, 191 1] 



NATURE 



\o\ 



you have the college, but where are the day students ? 

 You are blinding your eyes to facts : you have no boys in 

 Belfast who are prepared for modern business life in your 

 schools ; you have no boys fit to begin study at this college. 

 The sooner you set about such a kind of school work as 

 is necessar}' the better. 



I do not know what the Model School is like now, but 

 fifty years ago it produced better boys of the kind that 

 you now want than any school in the world. 



If you would sink your pride, and as a temporary 

 measure take here in the day time boys of fourteen and 

 teach them until they were seventeen, showing Ulster how 

 good modern-school teaching might be given, I feel sure 

 that you would make a rapid success. But such school 

 work ought to last only until your example would be 

 followed by outside schools. It strikes me, in fact, that 

 you ought to show both the primary and the continuation 

 and the secondary schools what they ought to do. 



There are now quite a number of secondary schools in 

 England and Scotland which provide science colleges with 

 just such intelligent students as they want. Our un- 

 scientific rulers have given an Intermediate Board to 

 Ireland which takes care that there shall be no such schools 

 Iv I'-. N't';iil\- all the cjiini I'.hglish public schools have made 

 a virfQrous attempt to give the kind of education which is 

 needed, but unfortunately the movement languished because 

 it is opposed to all the traditions of such schools, and there 

 are things lik? Latin which no schoolmaster will part with. 

 This is the reason why the modern sides of the English 

 public schools are such failures. 



"i'our difficulty here is felt in many other places, but in 

 some other places it has been grappled with and conquered. 



I repeat, it is in your power to make this the great science 

 school of the University, not merely developing applied 

 science, but developing scientific discovery in both physical 

 and biological science ; but your schools do not yet prepare 

 boys for such studies. 



At present the Queen's University of Belfast refuses to 

 recognise your students unless they pass entrance examina- 

 tions in Latin and French or Latin and German. The time 

 is coming when you yourselves will be able to confer a 

 science degree on your cleverest students, the students who 

 have had sufficient self-respect to neglect subjects which 

 for them were not educational. 



MOMENTUM IN EVOLUTION. 

 T T is a fact well known to 



widely separated groups of 



cli!.-i 1- t)-,^ course of their 

 !!'• "nd (if that K.nirse 

 ■ ■ . 'iicirniou-. imi-ra>e 

 :\Iil"ri'U. L;ia!U^ : 



: iiii li. ni, 1; ii aiii|i!ii 

 ])ii'i()il, MJai'- of 



■•■. ■.\],(] .•illUHl^- 



.:: i ill'- ^lill -,iir\-i\in: 

 a! i\'i- anal' mii^i -■ ai^- I 



iiii.ii'.i ^^ ;-.!;■,:. hiai , 



.tr\ il"\'' I ■ li'Mii- 



I 1 rrjltil' |M, il 



l)-a c and li-liii- : i.l (h.- hn 

 Babiiai^a. ' 



I '" ■■'■ 'ill. ram di'\'"li)jimi-iit n 

 :lil\ 111' allriluil' d tn 



. : ' :d'i d, I itir dail\ i'\| 

 :- in l.i-ii'A'ii 



.' '.A i)r. Srmlh Woo.Kv.ini - ;. 



'II of the British Association, lu 

 ii.irwin supposed that these tusk 



11 ion a< to render them u>elcs-. . 

 ive and used to pirry blows, b'li 



)f their enormous (lev.-lopmi.-ii; 



NO. 2200, VOL. 88] 



palaeontologists that many 



the animal kingdom have, 



evolution, and especially 



, shown a strongly marked 



in size.- \Vc see tljis in 



imoiiL^-st th'' artliropoda, in 



iiian-, in many reptiles of 



whicli attained a length of 



• t mammals in the extinct 



:^ ili])li,ants and whales. 



amiliar with similar pheno- 



iri;ans. suih as the- extra- 



aiid -pines on many of the 



I i;i^antic and grotesque 



inliill, and (In- tusks of 



f -vdini' ni-ans cf this kind 

 lie ariiiin ol si-xual selec- 



|i ri'-iiii' (il dui' (iwn species 



il; thai lliric is nn limit to 



nia\ i-nsu'- Irdin lie- un- 



t.H nil i'-s by citlii-r sex ; 



- alt. nipt to i-xplain all 



in this mamii-i'. 



iithi'is whiiii (dulil 



' 1' -fiMii- I'larticular 



sociation at 



! igicai 



. su<;h 



organ appears to have acquired some sort of momentum 

 by virtue of which it continues to grow far bevond the 

 limits of utility, although perhaps in some cases a new 

 use may be found which will assist the species in main- 

 tainmg itself in the struggle for existence. An enormous 

 mcrease of mere bodily size, however, seems in the long 

 run to be always fatal to the race, the place of which will 

 be taken by smaller and presumably more active forms. 

 The gigantic amphibians are all extinct, so are all the 

 really gigantic reptiles ; and of the gigantic mammals only 

 a couple of species of elephants and a few whales survive, 

 all of which are being rapidly exterminated in competi- 

 tion with man. 



Is there any justification in recent developments of 

 biological science for the belief that a race of animals may 

 acquire a momentum of the kind referred to which may 

 ultimately lead it to destruction? Is there some brake 

 normally applied to the growth of organisms and organs, 

 and, if so, are there occasions on which the brake may be 

 removed, leaving the organism to rush to destruction like 

 a car running away downhill? I hope to be able to show 

 some ground for believing that both these questions may 

 be answered in the affirmative. 



It is, I think, now generally accepted by physiologists 

 that the growth of the different parts of the animal body 

 is controlled by internal secretions or hormones, the pro- 

 ducts of various glands. Thus we know that disease of 

 the pituitary body in man leads to acromegaly, one of the 

 symptoms of which is great enlargement of certain parts. 

 The most dreadful of all diseases to which human beings 

 are liable, cancer, is essentially due to an unrestrained 

 multiplication of cells, and consequent abnormal growth 

 of tissue, which may very possibly be correlated with the 

 extent to which some specific controlling secretion is pro- 

 duced in the body. In short, we are justified in believing 

 that, in the individual, growth is normally inhibited or 

 checked by specific secretions, and that in the absence of 

 these it will continue far beyond the ordinary limits. 



The question next arises, Can we apply this principle to 

 the race as well as to the individual? I see no reason 

 why we should not do so, and, paradoxical as it may 

 seem, I think we may be able to explain the growth of the 

 organism as a whole, and of its various organs, beyond 

 the limits of utility, as an indirect result of natural selec- 

 tion. 



When a useful organ, such as the tusk of a wild boar, 

 is first beginning to develop, or to take on some new 

 function for the execution of which an increase in size 

 will be advantageous, natural selection will favour those 

 individuals in which it grows most rapidly and attains the 

 largest size in the individual lifetime. If growth is 

 normally checked and controlled by some specific secre- 

 tion, natural selection will favour those individuals in 

 which the glands which produce this secretion are least 

 developed, or at any rate least active. This process being 

 repeated from generation to generation, these glands (what- 

 ever may be their nature, and wi- may use the term gland 

 for anv cell or group of cells which produces a specific 

 secretion, whether recognisable as a distinct organ or not) 

 mav ultimately be eliminated, or ;it any _ rate cease 

 altogether to produce the particular hormone in question. 

 Moreover, this elimination mav lak.- place long before the 

 organ the growth of which is being favoured by natural 

 selection has reached the optimum size. When it has 

 reached this optimum it is certainly desirable that it should 

 grow no larger; but there is no longer any means In which 

 the growth can be checked: the inhibiting hormdiii is no 

 longer produced, the brake has been removed, an.l furllier 

 growth will take place, irrespective of utility, until, when 



the size of the organ gets too great to ' ' ' ••'•'h 



the well-being of the individual, na? i 



steps in and eliminates the race. TIt ., '* 



course, applies to the size of the body as a whole, as well 

 as to that of its constituent organs. Is it not possible that, 

 the normal checks to growth, being thus removed along 

 certain lines by the action of natural .selection, a definite 

 direction may be given to the course of evnlution which 

 the orcanism will continue to follow, irresp.^ctiv.- of 



organism 



n-ltMr-il cnh.rlinn 



be told I' 

 l.-ir organ \< 



