September 16, 1904.] 



SCIENCE. 



379 



ing revolution describes a vertical plane as 

 shown in Fig. D. 



If one wishes while the plant on the klinostat 

 is freed from the tropic effect of gravitation 

 to apply some stimulus for the study of a 

 tropic reaction, the stimulus should be em- 

 ployed so as to cause curves in the plane of 

 revohition ; for as soon as the tip of stem or 

 root deviates from the vertical plane, gravita- 

 tion seizes upon it to turn it to the horizontal. 



Neutralization of the Tropic Effect of Light. 

 — Experiments in which plants are rotated to 

 neutralize the tropic effects of gravitation have 

 been mostly carried on in the dark-room with 

 Seedlings. Such conditions and material are 

 easily obtained and managed. Sometimes, 

 however, when the experiments are prolonged, 

 and older plants are used, it is necessary to do 

 the work in the light to avoid the appearance 

 of pathological conditions. The requirements 

 for such work are as manifold as the end 

 sought and can not be considered here. It 

 may be indicated that when the experimental 

 plants are subjected to one-sided illumination 

 as before a window, there are several adverse 

 conditions that are not easily overcome. The 

 common statement that the plants are to be 

 rotated with the axis of the klinostat parallel 

 with the window in order to neutralize the 

 tropic effects of light leads to humiliation or 

 self-deception. If the part of the plant sensi- 

 tive to light is not at the center of rotation, 

 it alternately as it revolves approaches and re- 

 cedes from the light, receiving therefore more 

 light on one side than on the other, and re- 

 sponding with phototropic curves. Or if so 

 placed that it does not approach and recede 

 from the window, it may on the horizontal 

 klinostat, receive on one side its principal 

 illmnination from the sky and, on the opposite 

 side of the plant, from the earth, thus again 

 forming phototropic curves because of unequal 

 stimuli. Several plants in a pot revolving on 

 a klinostat with axis parallel with the win- 

 dow are likely to show curves because of the 

 shadows which the plants cast on one an- 

 other. Finally, the effort to neutralize the 

 tropic effect of both light and gravitation on 

 the same plants at the same time is so difS- 

 cult as to require very special attention to 



the management of the light, unless the work 

 is done in a plant-house with full exposure. 

 A klinostat, such as has been devised, giving 

 both vertical and horizontal revolution at the 

 same time is not a guarantee against faulty 

 results. Frederick C. Newcombe. 



University of Michigan. 



QUOTATIONS. 



THE PRESIDENTIAL ADDRESS BEFORE THE BRITISH 

 ASSOCIATION. 



Mr. Balfour's presidential address to the 

 British Association naturally recalls another 

 occasion in the history of that body when the 

 chair was filled, not exactly by a prime min- 

 ister, but by one who had been and very shortly 

 again became prime minister. There is a 

 marked resemblance between the address de- 

 livered at Oxford in 1894 by the late Lord 

 Salisbury and that delivered yesterday in the 

 seat of the sister University by his nephew and 

 successor in office. It is entirely right and 

 fitting that this should be the case, because on 

 both occasions the British Association has 

 listened, not to an expert in any one of the 

 sciences, but to a student of the true scientia 

 scientiarum. In a limited sense that proud 

 title may be bestowed, as it was yesterday by 

 Mr. Balfour, upon the science of physics. But 

 the real scientia scientiarum consists in the 

 assimilation by men of broad and sound gen- 

 eral culture of the best and most assured re- 

 sults of the labors of specialists in many fields 

 of research, and in the application of these 

 results to life and conduct in domestic affairs, 

 and to the solution of imperial problems in the 

 wider arena of statesmanship. Of the count- 

 less millions who own allegiance to the king 

 there is no man so deeply bound by duty and 

 responsibility to master that difficult science 

 as the prime minister of Great Britain. The 

 obligation, it must be confessed, has sat very 

 lightly U:pon many holders of that high office. 

 We would fain hope that the appearance of 

 two prime ministers in succession, showing 

 incontestably that they possess a genuine ap- 

 preciation of the vital necessity for knowledge 

 in the direction of affairs,' may be taken as a 

 sign that a higlier standard than that of 

 political dexterity in appealing to ignorance 



