436 



NATURE 



[March 12, 1908 



of hostile criticism and alternative hypotneses tiir- 

 nislicd b}- anatomists and microscopists of great sciqn- 

 tific repute. Prof. Osborn is, however, fully con- 

 vinced of the ultimate triumph of the theory ; and, 

 indeed, goes so far as to state that, in his opinion, 

 •• the evidence in favour of it is so overwhelming that 

 primitive trituberculy is no longer an hypothesis or a 

 theory, but an established fact." 



That a theory, although established on wliat appears 

 to be a firm basis of fact, may require revision in 

 certain details is a matter of everyday experience, 

 .ind our author is fully prepared to admit such emenda- 

 tions in this particular case so soon as the necessity 

 can be proved to be imperative. One of the points 

 against which criticism has been concentrated is the 

 author's view that the apex of the triangle in both 

 the upper and the lower molars represents the single 

 cone of the ancestral reptilian tooth. In the case of 

 the lower teeth, embryological evidence coincides with 

 I'rof. Osborn 's theoretical view; but as regards the 

 upper molars the testimony of embryology points to 

 the conclusion that, at least in many groups, the 

 antero-external, in place of the internal, is the primitive 

 element. The author meets this and other objections 

 by the candid statement that the five great principles 

 on which the theory was originally based "do not 

 stand or fall together '"; one or more may go, or have 

 to be modified, without imperilling the hypothesis as 

 a whole; and even if the cusps ultimately prove not 

 to be strictly homologous with one another in different 

 groups, " the homological nomenclature should be 

 retained for convenience because it has found its way 

 so largely into literature." 



The homology and origin of the cusps are, however, 

 by no means the sole object of attack on the part of 

 critics. .Among other objections, reference may be 

 made .to the multitubercular theory, according to 

 which molars have tended to simplify rather than to 

 grow more complex. This hypothesis is met by the 

 author, and we think rightly, with a direct negative, 

 and certain other objections receive equally summarv 

 treatment. 



As regards the plan of the work, it is important to 

 notice that the contents are in the main formed bv 

 separate papers on trituberculism, which have been 

 arranged in chronological order, and, where neces- 

 sary, brought up to date by intercalary notes. This 

 plan has its advantages and disadvantages. Its 

 advantages are that the history of the controversy is 

 easy to follow, while the disadvantages are manifest 

 ill the shape of a considerable amount of repetition. 

 We are also left in doubt at the end of the volume 

 ai to what the author's present views really are with 

 regard to several points on which his theory has been 

 challenged. 



To do anything like justice to tlie work demands 

 much more space than can be given to it in this 

 notice. All that can be done is therefore to direct atten- 

 tion to its importance and interest, and at the same 

 time to express the opinion that the author has suc- 

 iceded in placing trituberculism on a much men 

 -ecure and unassailable basis than it ever previousl\ 

 occupied. I,; i^ 



NO. 2002. VOL. 77] 



OUR BOOK SHELF. 

 Nature and Development <>/ Plants. By C. C. Curtis. 



Pp. V-1-471. (New York: Henry Holt and Co.. 



1907.) 

 The author of this book has set himself a definite 

 task, namely, to give an account of plant life, with 

 special reference to that aspect which presents it as .i 

 w^orking organism. Dr. Curtis is to be congratu- 

 lated on the successs^\ilh which he has achieved his 

 object, for he has produced an excellent and readable 

 book which may be confidently recommended for the 

 use of junior classes in this country. Naturally, some 

 of the actual examples may prove unfamiliar to the 

 student, but the majority of the plants chosen for 

 illustration are readily accessible to all. 



The " nature of the plants " occupies the first part 

 of the book, and it is this portion which strikes us as 

 especially good. The second part is devoted to the 

 development, meaning thereby the phylogenetic classi- 

 fication of the vegetable kingdom; and here again 

 Dr. Curtis has, we think, contrived to sustain the 

 interest in a branch of botany which, as treated in 

 elementary works, is often intolerably dull. He ha-i 

 introduced a certain amount of advanced work in this 

 part of the book, though with a judicious absence or 

 unnecessary detail. 



Perhaps a degree of emphasis, rather greater than 

 is warranted by our knowledge. Is laid on the relation 

 between alternation of generations and chromosome 

 reduction. The discussion also as to the meaning of 

 unit characters and the method of their inheritance 

 strikes us as too formal and dogmatic to be very 

 useful. But these are small blemishes in a work 

 where there is so much that merits praise. 



The numerous and excellent illustrations form ;i 

 distinct feature of the book, but we note two amongst 

 them which might well be replaced. Fig. 43, and 

 the text which accompanies it, represent a very dia- 

 grammatic and not very normal mode of secondary 

 thickening, whilst Fi.g. .S5 certainly ought to be re- 

 drawn. -A seedling castor-oil ])lant is not the furry 

 object there represented. . J. B. F. 



Tin' Diseases of Animals. B\ Nelson .S. Mayo. Third 



edition. (New York: The Macmillan Company; 



London : Macmillan and Co., Ltd., 1907.) Price 



6s. 6d. net. 

 This work, which purports to be one of popular advice 

 on the care and common ailments of farm animals, 

 is written entirely from the .American point of view, 

 and deals with .American methods principally, in most 

 distinctly .American orthography. It cannot be doubted 

 that its usefulness to the British rural public, not less 

 than the pleasure of reading it, are considerably 

 lessened thereby. It is decidedly irritating to readers 

 on this side of the .Atlantic to see such abominations 

 as "sulfur," " esophagus," " sulfate," "mold," and 

 others of a similar kind. There is, nevertheless, a 

 good deal of useful and practical information en the 

 care of animals and farm stock which the farmer 

 would do well to know, no matter in what part of tlie 

 world he carries on his occupation. In fact, that por- 

 tion of the book which deals with feeding, watering, 

 exercise, and the hygienic care of domestic animals, 

 both stock and pets, is in our opinion by far the most 

 useful to the general reader. In this section dogs, 

 cats, rabbits, hares, guinea-pigs, and poultry are 

 dealt with, in addition to the farm animals proper. 



The photographic illustrations of the animals them- 

 selves are good, but some of those representing morbid 

 conditions are of little value, for example," that of 

 tuberculosis of the lung (p. 380), which could give no 

 assistance to the non-expert. 



In a work of tliis kind it is doubtless difficult to 



