August 25, 1911] 



SCIENCE 



245 



and California and tlie latter region is prom- 

 inent in the production of barley grain for 

 malting. The Imperial Valley produces large 

 quantities of excellent barley. 



The ancient and still commonly prevalent, 

 though clearly illogical, confusion of osmotic 

 with hydrostatic pressure finds, on page 69 of 

 this text, its most recent expression. We are 

 told that so long as water may be absorbed 

 there is exhibited in plant cells " an hydro- 

 static pressure known as turgor. . . . Turgor is 

 then the expression of the osmotic pressure of 

 the cell." The Van't Hoil theory of osmotic 

 pressure (gas-pressure theory) has been briefly 

 stated in the preceding paragraph, so that the 

 reader will picture turgor as brought about 

 by the tendency of the solutes of the cell to 

 expand within the limits of the solvent, the 

 former substances being imprisoned within 

 the plasmatic membrane, through which they 

 do not pass. But the reader is now told that 

 the internal pressure which produces turgor is 

 hydrostatic, which can only mean that it is 

 due to water. He remembers that the plas- 

 matic membrane is permeable to water and 

 becomes hopelessly muddled.' 



Serious misconception may arise from the 

 following, which occurs on page 440 : " The 

 method of reducing toxicity by solid particles 

 [in water-culture solutions] is usually denoted 

 [^sicl adsorption." Of course the general phe- 

 nomenon of adsorption is well-known phys- 

 ically and receives a large amount of atten- 

 tion in the recent hand-books of colloid chem- 

 istry, so that the implication that this phe- 

 nomenon is knovm only, or even mainly, in 

 connection with physiological solutions, is 

 much to be regretted. Following the above 

 sentence comes a brief statement of the usual 

 explanation of adsorption, and then we enter 

 again upon troubled ground, in the statement 

 that " another explanation is that the solid 

 substances offer obstacles to the free move- 

 ment of the solvent particles." Obviously, 

 " solvent " should be replaced by solute, but, 



^For a discussion of a similar statement, made 

 years ago, see Livingston, B. E., "The Role of 

 Diffusion and Osmotic Pressure in Plants, p. 31, 

 Chicago, 1903. 



even with this modification, the sentence can 

 not stand, for it is well established that the 

 effect of solid particles (such as lamp-black 

 and quartz flour) upon a toxic solution re- 

 mains manifest after their complete removal 

 from the solution.^ 



In general. Professor Duggar's treatment of 

 the subject is exceptionally safe; we find no 

 dogmatic statements in the entire book, and 

 the careful wording will hardly fail to impress 

 upon the student the importance and desira- 

 bility of that inestimable attribute of the 

 trained thinker, the habit of suspended judg- 

 ment. The fact that the author employs the 

 word suggest where many others would have 

 written show or demonstrate, indicates clearly 

 the wholesome tendency of the treatment. 

 Indeed, some critics will probably find fault 

 with many paragraphs because of the indefi- 

 nite conclusions reached; the method of cau- 

 tion is carried farther than it need be at cer- 

 tain points. The reviewer believes, however, 

 that we touch here upon one of the moat com- 

 mendable characteristics of Professor Dug- 

 gar's work. 



Another admirable quality which deserves 

 special mention here is the almost complete 

 avoidance of teleological or anthropomorphic 

 implications. We find no " adaptations " here 

 discussed, and seldom is a process said to 

 occur " for " future " needs." While not ab- 

 solutely free from teleological lapses — here 

 and there occur such statements as this, that 

 "the seed and tuber are effective propagative 

 devices "—yet the work of Professor Duggar 

 has clearly shown, once for all, that it is quite 

 possible and practicable to discuss plant phe- 

 nomena without indulging in those anthro- 

 pomorphic colorings which characterize a still 

 very prevalent type of biological writing. At 

 the same time, our author does not make his 

 book unreadable to the beginner by seeking to 

 put all statements in terms of pure energetics. 

 The secret of his success in this direction lies 

 perhaps mainly in the fact that he develops 

 human interest by emphasizing the usefulness 

 of plants to man, rather than by virtually 



= For example, see Bulletins 28 (1905) and 36 

 (1907), Bureau of Soils, U. S. Dept. Agric. 



