Literary Notices. 529 



a potometric tube, by which the constant changes of suctional activity are measured; 

 (3) a contrivance by means of which the movements of the water-index with their 

 time relations, are recorded" (p. 364). 



In the Hght of a variety of observations concerning the changes in suctional 

 response which are exhibited by plants under stimulation the author concludes 

 that the ascent of sap is an excitatory phenomenon due to the stimulation of the 

 root by contact with the soil, friction of the growing organ, excessive turgidity, and 

 chemical action. 



Similarly, growth is described as a phenomenon of multiple response. AH 

 growth movements are the indirect effects of stimulation of the organism. 



A microscope recorder was employed by the author in his work on the tropisms 

 of plants. He was thus enabled to obtain graphic records of extremely slight move- 

 ments. By means of the response-curves which this instrument gave him Bose 

 describesthe varioustropismsofplants. He states that plants exhibit phototropism, 

 chemotropism, galvanotropism, etc., as do animals, and, further, he insists that the 

 phenomena in the two cases are the same in principle. Again I may quote at length 

 from the text. "Though at first sight it would appear as if there were no connection 

 between the simple responsive curvatures of radial organs and the apparently com- 

 plicated responsive movements of swimming, yet on closer analysis we shall find 

 that there is little essential difference between the two; for we have seen that growth 

 itself, or growth-curvature, is simply a phenomenon of multiple responsive move- 

 ments, which, owing to the rapidity of the individual responses, appears continuous. 

 Hence, when, under moderate stimulation, the organ moves toward the light, or 

 exhibits a positive response, this means that the resultant of its multiple movements 

 is towards the stimulus, like the resultant movement of the ciliated organism 

 towards light. Similarly, under strong photic stimulation, the negative heliotropic 

 movement of the organ corresponds to the swimming of the ciliated organism 

 away from the light. In the intermediate case, again, where the stimulated organ 

 shows no resultant curvature, but oscillates about a mean position, we have an 

 instance which is paralleled in the case of the ciliated organism, by alternate swim- 

 ming backwards and forwards" (p. 695-96). 



Critical comments are now in order. I find it extremely difficult to judge of the 

 value of Bose's work. What I most feel the need of is a few hours with him in his 

 laboratory, and the opportunity to observe some of his experiments. His methods 

 certainly are most ingenious, and they appear to have given him very valuable 

 results. However, the reader is impressed with the fact that unless the experi- 

 menter was extremely careful at every point in his work serious errors must have 

 appeared in the records. The methods are so delicate that a very slight change 

 in the adjustment of the apparatus must inevitably produce a great change in the 

 record. 



The author has worked to prove that plants respond essentially as do animals. 

 At every point he attempts to show that one or another of his conjectures is sup- 

 ported by experimental results. After reading for a time one begins to wonder 

 whether the theory and conjecture and conclusion portion of the book does not 

 weigh too heavily for the demonstrated facts. "One gets such wholesale returns 

 of conjecture out of such a trifling investment of fact" that the experiments come to 

 take a secondary place. It is quite possible that Bose has fully established his 

 points and that the weakness which I have mentioned results from his method of 



