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SCIENCE 



[N. S. Vol. XL. No. 1037 



forming the plateaux. The diagram referred 

 to would seem to be a limiting case of the 

 author's indifference to rational geodynamics, 

 yet in the introduction to Part II. he states 

 that " Throughout the preceding chapters the 

 attempt has been made to admit only such 

 descriptions and classifications as are direct 

 expressions of objective facts." 



The second part of the book begins with a 

 discussion of the possible temperature and con- 

 stitution of the earth, which he concludes con- 

 sists superficially of an outer " acid " or 

 " granitic " shell with a partial covering of 

 stratified rocks, underlaid by a liquid "basal- 

 tic " shell. He states that the phenomena of 

 intrusion and of rock variation can all be ex- 

 plained by the interaction of these shells, to 

 demonstrate which the succeeding chapters 

 were written. The hypothesis of concentric 

 zones of granitic and basaltic magmas is like 

 those of von Waltershausen, Durocher and 

 others, and the synthetic features are similar 

 to those of von Cotta. These hypotheses were 

 evolved before the closer study of igneous 

 rocks had shown the error of their funda- 

 mental conceptions. This modern knowledge 

 Professor Daly ignores, and any attempt to 

 convince him of his mistake would involve 

 a course of instruction which he does not ap- 

 pear to desire. It is not too much to say that 

 the statements he makes in support of his 

 hypotheses regarding the constitution of the 

 lithosphere, the processes of magmatic intru- 

 sion, of overhead stoping, assimilation and 

 subsequent differentiation appear to the 

 writer to be in part fundamentally wrong and 

 in many cases thoroughly misleading to the 

 reader. It would be an extensive undertaking 

 to criticize his elaborate and voluminous argu- 

 ments in detail, and it would be a task the 

 writer does not care to attempt. 



His discussion of " abyssal injection " which 

 is based on the assumption that the earth con- 

 sists of a " relatively thin crust overlying a 

 fluid basaltic substratum of unknown thick- 

 ness " (p. 192), and the diagrams illustrating 

 his conception of the process, as well as of 

 that of batholithic intrusion, and also the 

 scheme of rock genesis which is given in Part 



III., are all based on the principle of contrast- 

 ing two assumed antithetical qualities, or 

 groups of properties, such as a " solid crust " 

 and a " liquid substratum," an " acid " rock 

 mass and a " basic " rock magma ; correspond- 

 ing to the two magma hypothesis of Bunsen 

 with its synthetic corollaries. It is a system 

 which does not appear to be in harmony with 

 modern notions of evolution, but finds its 

 counterpart in metaphysics, with its antithet- 

 ical right and wrong. It seems to the writer 

 that physics, not metaphysics, should furnish 

 the basis for modern petrology. 



In calling his speculations an " Eclectic " 

 theory Professor Daly has not distinguished it 

 from any other complex theory of the present 

 day, which in the nature of science must be 

 derived from many other theories or hypoth- 

 eses, previously enunciated. All modern complex 

 theories are eclectic, or are but slight modifica- 

 tions of previous ones. The theory to which 

 that of Professor Daly is most closely related, 

 as he points out, is that of Loewinson-Les- 

 sing, published fifteen years ago, which its 

 author called a " synthetic-liquation theory of 

 differentiation," a name which has the merit 

 of being descriptive. 



The third part of the book before us outlines 

 the result of applying the author's theory to 

 the problem of petrogenesis. The result is a 

 most remarkable distortion of petrographic re- 

 lationships, and a thoroughly artificial scheme. 

 The grotesqueness of the conclusions might be 

 relied on to condemn the process of reasoning 

 by which they have been attained were it not 

 for the eminence of the author, the magnetism 

 of his personality, and the effectiveness of his 

 address, which give a seriousness and force to 

 his writings that will carry conviction to many 

 readers who have no means of independent 

 judgment, both as to the correctness of his di- 

 rect statements in each case and as to which 

 are realities and which subjective conceptions. 



With Professor Daly's tireless energy and 

 vigorous methods of attack; with the acknowl- 

 edged honesty of his conviction as to the cor- 

 rectness of his reasoning, but with his lack of 

 discrimination between the relative values of 

 objective realities and subjective conceptions; 



