222 



SCIENCE. 



[N. S. Vol. XIX. No. 475. 



lines, does not hesitate to declare that 'for the 

 harmony which exists between the living con- 

 ditions of organisms and their raorphological 

 and physiological characters there is at the 

 present time no other scientific explanation 

 than natural selection.' In the second book, 

 on the other hand, Morgan is firmly convinced 

 that as a means of accounting for adaptations 

 the doctrine of selection is largely to be dis- 

 carded. Morgan represents the newer school 

 of evolutionists, and from this standpoint 

 his book has a timely value, for it is the first 

 non-technical work of its kind. Whether he 

 proves his case satisfactorily — for the work 

 is pa7-ti pris throughout — is a question which 

 each critic must answer. But all will agree 

 that his work will find its place on the general 

 bookshelves side by side with the volumes of 

 Romanes, Lloyd Morgan, Spencer and Wallace. 

 Morgan, as he states in his preface, was 

 early led to a belief in the inadequacy of 

 natural selection from his studies upon re- 

 generation, for this process often concerns 

 itself with structures which play no part in 

 strict Darwinism. The author now aims to 

 explain some of these ditficulties by muta- 

 tions.* Thus, keeping in mind especially the 

 results of De Vries, Morgan emphasizes the 

 probability of mutations having occurred 

 broadcast under infinite conditions of manner, 

 degree, place and time. Such mutations pro- 

 duced series of creatures which were suited or 

 unsuited to their particular locality, or were 

 perhaps indifferent. Some, like Kallima, were 

 even better adapted to their neighborhood than 

 necessity for survival demanded; others were 

 imperfectly adapted, but surviving in spite, 

 e. g., of bright colors, asymmetry or compli- 

 cated reproductive processes. According to 

 such a doctrine of mutations organic forms 

 succeed one another kaleidoseopically, their 

 variability becoming largely arrested between 

 the definitely marked periods of change. Thus, 

 if a species be compared to a facet upon which 

 a polyhedron is balancing, the species, like 

 the facet, may oscillate within definite limits. 



* The Lamarekian hypothesis is given little im- 

 portance: 'I am not sm-e that we should not be 

 justified at present in claiming that the theory 

 is unnecessary and even improbable.' 



But if the limits of variation are transcended, 

 the entire polyhedron changes its position and 

 comes to equilibrium on a new facet. This 

 plan of variation forms the undercurrent of 

 Morgan's philosophy; through it he sees ap- 

 pearing structures, forms and habits, which 

 have no ' selective value,' their purpose or 

 utility may be partly or wholly nil, ' for we 

 can not measure the organic world by measure 

 of utility alone,' yet they appear as perfectly 

 and as plentifully as the crystal-forms of snow. 

 Granted then a galaxy of mutations some of 

 them will fit their surroundings with marvel- 

 ous accuracy. And with this in mind Mor- 

 gan develops what he believes is a probable 

 answer to many of the puzzles of shape and 

 symme^-y, the mutual adaptation of colonial 

 forms, degeneration (those mutations only 

 . surviving which ' we may almost say, have 

 been forced ' into a parasitic environment, 

 ' for these degenerate forms can only exist un- 

 der such conditions'), coloration, life-length, 

 regeneration, individual adjustments, second- 

 ary sexual characters and even of sex itself. 



It is obviously impracticable for a reviewer 

 to consider more than the barest outlines of 

 a work which touches many fundamental view- 

 points. Each of the dozen chapters of the 

 present book contains enough to warrant sep- 

 arate reviews and reviewers. And each critic 

 will find little trouble in pointing out some of 

 the many ' pitfalls ' referred to in Morgan's 

 preface. For discussions in evolution have 

 long since shown that facts may be read in 

 difl^erent ways. 



There are general features in which the 

 present volume deserves warm praise, as in 

 providing a mass of helpful examples, and in 

 urging attractive arguments against many 

 ' purposeful ' or ' useful ' variations, and above 

 all things in considering critically the doc- 

 trine of sexual selection, furnishing against 

 the latter — in spite of lack of reference to 

 Cunningham's work — the most serious objec- 

 tions hitherto given. There are other fea- 

 tures, however, in which improvement might 

 well have been made. Regrettable is a gen- 

 eral dearth of exact references — there are, in 

 fact, not a dozen citations in all. And espe- 

 cially regrettable, in view of the scope of the 



