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Show CHAPTER XIV .FUNDAl\IENTAL PROBLEMS IN llELATION TO VARIATION AND HEREDITY . . . nd ob. ections--Mr. Herbert Spencer's fad or~ Fundamental ddncult~es aD' ~ 1 effects of withdrawal of nalural of organic evolutwn-. tsuset· alJ~c se "monrr wild animals- DifTi <·nlty . S ed efleds o l lSU .. b . selectiOn- uppos ' b .· tion and selection-Direct adton as to co-ad~ptation ~¥~~r:sA!e~·~~~~1 school of evolntionists-:-Origin of the environment lates-Su osecl action of animal in telhgcnccof the feet of the ung~ flf p ptl e envl·ronmcnt-Professor Ged<l t>s's t l d · ·ect m uence o 1 Semper on 1e. n. . 1 t ·-ObJ'ections to the theory-On the tl ·y of vanatwn m P an s !f t f · • 1. .e 0.1 f sp.m es-V an.a t 'I On anu,, selection overpower. th.e e. ec. s o u.s c ougm o . d t' f the environment m umtatmg vanaand disuse:-Snpp~se ae. tonf ~eredit -The cause of variation-Tile tions-WClsmann s th.eoJdY \ ·acters~The theory of instinct-Counon- heredity of acqmre c at, eluding remarks. forth and illustrated at some lcnuth the HAVIN.G now set the a lications of the development most rmpor~ant of ex lan!tlon of the broader and more hypothesiS . Itl l . thte' p ted by the oru:mic cr phenomena presen b generally m eres m::, 1. me of the more fundaml'nbtl ld opose to ( 1scuss so worb l ' we apnrd dr.f ficu 1t r.e s w hr' c h h"••v c recently been a<lclw·e.< .1 pro e~s . . It is the more neces ary to clu t lns, by emment nat~ra.hsts. t l cy to minimise the acLion of b th .0 1s now a one en ecause er . . th roduction of orc)'anic forms, am1 to natural· sel·e t ctiO1n em c ertae.m P f um1 a m cnt"l pl·inci11les of variation L• set up mfl s p a~l hich it is urge<l arc the real origina~ors or laws o grow l, wf d 1 't and of most of the v:u·.ICty h .. 1 r es 0 eve opmen , • · . of t e severa m . the ve<retable and animal longclom . of form ~nd structure I~ b~en seized upon by popular These vrews have, mmeovder, l. d't on the whole theory of writers to throw doubt an c rscre 1 OIIAP. XIV FUNDAMENTAL PROBLEMS 411 evolution, and especially on Darwin's presentation of that theory, to the bewilderment of the general public, who are quite unable to decide how far the new views, even if well established, tend to subvert tho Darwinian theory, or whether they are really more than subsidiary parts of it, and quite powerless without it to produce any effect whatever. The writers whose special views we now propose to consider are : (1) Mr. Herbert Spencer, on modification of structures arising from modification of functions, as set forth in his Factor·s of Organic Evolntion. (2) Dr. E. D. Cope, who advocates similar views in detail, in his work entitled 1'he Origin of the Pittest, and may be considered the head of a school of American naturalists who minimise the agency of natural selection. (3) Dr. Karl Semper, who has especially studied the direct influence of the environment in the whole animal kingdom, and has set forth his views in a volume on The Natur·al Conditions of Existence as they Affect Animal Life. ( 4) Mr. Patrick Geddes, who urges that fundamental laws of growth, and the antagonism of vegetative and reprodtJctive forces, account for much that has been imputed to natural selection. We will now endeavour to ascertain what are the more important facts and arguments adduced by each of the above writers, and how far they offer a substitute for the action of natural selection ; having done which, a brief account will be given of the views of Dr. Aug. \V eismann, whose theory of heredity will, if established, strike at the very root of the arguments of the first three of the writers above referred to. Mr. Ilerbe1·t Spencer's Factm·s of Organic Evolution . Mr. Spencer, while fully recognising the importance and wide range of the principle of natural selection, thinks that sufficient weight has not been given to the effects of u e and disuse as a factor in evolution, or to the direct action of the environment in determining or modifyino· orcranic structures. As examples of the former clas. of actions, he adduces the decreased size of the jaws in the civilised races of mankind, the inheritance of nervous disea e produced by overwork, the great and inherited development, of the udders in cows and goats, and the shortened legs, jaw , and snout in |