September 25, 1890] 



NATURE 



517 



if an attempt had been made to show that geotropism, 

 heliotropism, hydrotropism, &c., are all parts of one 

 phenomenon : we find, however, no hint that these modes 

 of growth are now regarded as so many different forms 

 of reply to stimulus. Under geotropism. Knight's experi- 

 ment is not even mentioned, and the student would 

 probably never discover that gravitation as a stimulus 

 had anything to do with the matter. Prof. Goodale (p. 

 392) believes that a negatively geotropic organ curves 

 upwards because the "nutritive fluids" collect "in 

 greater amount in the cells upon its lower side." In the 

 case of positively geotropic organs he seems to believe in 

 the ancient doctrine of plasticity, according to which a 

 root bends down just as a tallow candle collapses in warm 

 weather. He connects this view with the so-called 

 absence of tension in roots ; from this we should be led 

 to suppose that he believes all roots to be positively 

 geotropic, but this does not seem to be the case, for he says 

 that " it is a significant fact that in the case of certain 

 branches from roots the direction of growth is oblique." 



The treatment of heliotropism is on the same level ; he 

 believes in De Candolle's exploded theory, which de- 

 pends on the fact that growth is favoured by shade, and 

 according to which the difference in illumination on the 

 two sides of the organ is not a stimulus, but the direct 

 cause of curvature. 



In the chapter on the movements of plants the account 

 of the clinostat is not good. Prof. Goodale omits to 

 mention the especial merit of this instrument, viz. that 

 it counteracts at one and the same time the eff"ects of 

 one-sided illumination and of the gravitation stimulus. The 

 illustration of the clinostat is singularly unfortunate, being 

 in fact Sachs's drawing of secondary roots bending, under 

 the influence of centrifugal force, in Knight's experiment. 

 In the discussion on circumnutation it is a pity that no 

 allusion is made to Wiesner's -careful critique on the 

 " Power of Movement in Plants." In the same way a 

 modern account of twining plants should give references 

 to Baranetzky's and Wortmann's papers. 



Chapter ix., on the " Transfer of Water," is an im- 

 provement ; still the heart of the matter is hardly touched, 

 and the student who relies on this discussion will be but 

 indifferently instructed. He will not, for instance, have 

 any clear idea that the question whether or no the trans- 

 piration-current travels as water of imbibition is or ever 

 was a problem deserving of especial attention. 



Further on we find De Vries's experiments on the wither- 

 ing of stems cut in air, and on their preservation from 

 withering when cut under water, but without any reference 

 to von Hohnel's work on negative pressure, which has 

 such important bearings on this point, and indeed on the 

 whole question of water-transfer. In the section on the 

 mechanism of stomata we miss the names of Schwendener 

 and Leitgeb ; and under the heading " Relation of Age of 

 Leaves to Transpiration," there is no clear explanation of 

 the relations of stomatal and cuticular transpiration. 



In chapter x. a very fair account is given of the assimi- 

 lation of carbon. The author deserves credit for giving 

 the passage in which, in 1 8 1 7, the word chlorophyll was pro- 

 posed ; just as in another part of the book he gives the 

 passage in which the itvm protoplasm was first employed. 

 With regard to chlorophyll we think it a pity that any 

 encouragement should be given to the confusion between 

 NO. 1 09 I, VOL. 42] 



chlorophyll and chloroplasts by such a remark as the fol- 

 lowing : " The term chlorophyll originally applied to the 

 pigment rather than to the substance which contains it, is 

 now used indifferently to denote the coloring-matter and 

 the portions of protoplasmic mass which are tinged by 

 it." This statement is all the more unnecessary because 

 he gives on the next page a useful table of the plastid- 

 nomenclature of Schimper, Meyer, &c. Pringsheim's 

 hypochlorin theories are reproduced, but without the word 

 of warning that should accompany such speculations in a 

 book intended for students. 



There is a fair account of Timiriazeff's and of Engel- 

 mann's work on assimilation ; but we doubt whether it 

 would induce the beginner to appreciate the extraordinary 

 interest and importance of Engelmann's researches. The 

 section ends with an outline of the "early history" of 

 assimilation, which contains some interesting quotations 

 from Priestley and Ingenhousz, 



The section on the " Appropriation of Nitrogen " suffers 

 grievously from the fact that the nutrition of Fungi is left 

 out of account. The " Synthesis of Albuminous Matter" 

 is inadequately treated, and the same must unfortunately 

 be said of the action of ferments ; and with regard to 

 the origin of alkaloids it would have been better to have 

 given the well-known hypothesis that they are waste pro- 

 ducts, rather than to have left their meaning in complete 

 obscurity. 



Chapter xiv. is devoted to reproduction : the author 

 seems to have been hampered with the fear of over- 

 lapping the forthcoming book on Cryptogams, as he 

 confines himself almost entirely to the higher plants. 

 He gives, in a footnote, some account of the reproduction 

 of Spirogyra, Fucus, Nemalion, Funaria, Pteris, and 

 Selaginella, but gives no idea of the connection between 

 this latter form and the Spermaphytes. It is clear that 

 without a free use of the lower forms it is impossible to 

 give such a generalized view of the reproduction of plants 

 as is appropriate in a physiological text-book. 



In discussing the colours of flowers, it would have 

 surely been better to have given H. Miiller's interesting 

 generalizations in place of the barren statistics of Kohler 

 and Schiibeler. The chapter concludes with some useful 

 facts on hybridization. 



The last chapter in the book consists of a few pages on 

 germination. The greater part of this discussion might 

 with advantage have been divided among those parts of 

 the book which deal with the general conditions of plant 

 life and with metabolism. Of the interesting growth- 

 phenomena of germination, such as the protrusion of the 

 radicle, the manner in which the cotyledons are freed 

 from the seed-coats, &c., some account should have been 

 given, even at the risk of overlapping vol. i. of the Text- 

 book. 



In spite of a general faultiness of the kind indicated the 

 book is not without value. It is clearly written, and con- 

 tains the substance of a large number of books and papers, 

 references to which are given at the foot of the page 

 (instead of at the end of the chapters) to the very great 

 convenience of the reader. Many of these references to 

 older papers are likely to be useful, and of salutary effect 

 on the rising generation of botanists, who are somewhat 

 inclined to overlook the work done in the days of their 

 grandfathers. 



