March 24, 1910J 



NATURE 



115 



Summarising the argument of his address, Prof. Herrick 

 said : — In our analysis of the behaviour of animals and 

 its mechanisms we start with the tropism and the reflex. 

 This type of response is in some of its simpler phases in- 

 distinguishable from the reactions of dead machines to the 

 forces which actuate them ; but the more complex reflexes, 

 on the other hand, grade over into those behaviour types 

 which we call intelligent. No one has yet succeeded in 

 formulating a clear-cut definition of the limits of the reflex 

 • at either its lower or its higher extreme, and perhaps no 

 one ever will, for the whole list of behaviour types from 

 machines to men probably forms a closely graded series. 



Even the simpler reflexes exhibit a measurable refractory 

 phase or pause in the centre where the afferent impulse is 

 made over into the efferent. WTien reflexes are com- 

 pounded, there is another factor which may tend to modify 

 or delay the response. This is the dilemma which arises 

 when two or more reflex centres are so related that a 

 given afferent impulse coming to one of them may take 

 any one of several final common paths to the organs of 

 response. The reflex response which actually emerges in 

 such a case will generally be the adaptive one, i.e. the 

 one which is best for the organism. The selection of the 

 adaptive response in such a case may be termed physio- 

 logical choice, and it always involves a lengthening of the 

 refractory phase. In the neural tensions of the refractory 

 phase of physiological choice we find the germs of the 

 complex anticipatory reactions which in turn have nurtured 

 the awakening intelligence. 



The comparative study of animal behaviour in the 

 broadest sense of the term is as essential as other branches 

 of physiology to the comprehension of animal structures, 

 and the enlargement of our knowledge of scientific 

 fact in this field will contribute greatly to the more perfect 

 integration of the three great branches of biology — 

 anatomy, physiology, and psychology — and the correlation 

 of the whole with other departments of knowledge. Our 

 philosophy of nature is sound just in proportion as we 

 succeed in effecting these correlations of experience. 



Response to Chemical Stimulation. 



In Section G (Botany) the president. Prof. H. M. 

 Richards, of Columbia University, New York, addressed 

 the members on the nature of response to chemical stimula- 

 tion. Few, if any, physiologists would, he said, to-day be 

 inclined to deny the ultimate chemical nature of the 

 response of protoplasm to any form of stimulus. It is the 

 purpose here to limit the examination of chemical irrita- 

 tion more especially to actual concrete chemical substances 

 brought into relation with living protoplasm, and to inquire 

 somewhat more particularly into their mode of action and 

 the nature of the changes which they induce. The import- 

 ance and fundamental nature of these reactions cannot be 

 doubted. For this purpose we may include in the list all 

 those substances which it may reasonably be believed 

 Induce, by their chemical action, constitutional changes in 

 protoplasm. These substances may be mineral salts, 

 organic compounds of great diversity of structure, including 

 anaesthetics, which have been, perhaps, wrongly placed 

 in a special class, and even gases of a simple constitution. 

 They may be crystalloidal, electrolytes or non-electrolytes. 

 or perhaps even colloidal. 



There are some points in regard to the normal food 

 supply which have a direct bearing upon the question of 

 chemical stimulation, as defined even in its restricted sense. 

 In the case of some of the necessary food materials the 

 concentration may vary within relatively wide limits before 

 the effects of a lack or excess of these substances are 

 observable. In such cases the increase necessary to pro- 

 duce a reaction may readily be so great as to involve a 

 material increment in the isotonic coefficient of the solu- 

 tion, and thus confuse any result produced by any direct 

 chemical stimulus with those initiated by the change in 

 osmotic pressure. It is known, however, that some of the 

 necessary salts which are required by the plant in relatively 

 small quantities may, if the concentration be raised above 

 the normal point, cause a secondary stimulation of growth, 

 and eventually, if the increase be continued, become 

 inhibitory after the manner of poisons. 



In its restricted sense, chemical stimulation may be said 

 to deal with the effects of chemical agents which are not 

 only not necessary, but which may be positively deleterious 



NO. 2108, VOL. 83] 



to the organism — poisons, in short. It has been estab- 

 lished that many, if not all, classes of substances which 

 exert a toxic action on protoplasm will become stimulatory 

 if presented to the cells in sufficiently small doses. Some- 

 where between an infinitesimally weak solution which pro- 

 duces no reaction to the toxic dose which kills there is 

 a stimulative optimum which gives the maximum of re- 

 action. The question is not the possible ultimate lethal 

 effect of these poisons, but how far they may serve to 

 excite the protoplasm to extraordinary activity. The 

 amount required to effect the latter result will naturally 

 vary with the substance, certain mild poisons possibly never 

 affecting the plant beyond the stage of stimulating growth, 

 no matter how high a concentration was employed. 



Prof. Richards concluded by dealing in some detail with 

 the influence of chemical stimulus on the physiological 

 activities of the plant, and why and in what manner the 

 specific irritants used affect the quantitative, and even 

 perhaps the qualitative, formation of enzymes. 



Racial Differences in Mental Traits. 



In Section H (.\nthropology and Psychology) Prof. R. S. 

 Woodworth, of Columbia University, the president of the 

 section, in his address took up the question of racial 

 differences in mental traits. 



Our inveterate love for types and sharp distinctions, he 

 said, is apt to stay with us even after we have become 

 scientific, and vitiate our use of statistics to such an extent 

 that the average becomes a stumbling-block rather than 

 an aid to knowledge. We desire, for example, to compare 

 the brain weights of whites and of negroes. We weigh 

 the brains of a sufficient number of each race — or let us, at 

 least, assume the number to be sufficient. When our 

 measurements are all obtained and spread before us, they 

 convey to the unaided eye no clear idea of a racial differ- 

 ence, so much do they overlap. If they should become 

 jumbled together, we should never be able to separate the 

 negroes from the whites by aid of brain weight ; but now 

 we cast up the average of each group and find them to 

 differ, and though the difference is small, we straightway 

 seize on it as the important result, and announce that the 

 negro has a smaller brain than the white. We go a step 

 further, and class the white as a large-brained race, the 

 negro as a small-brained. Such transforming of differences 

 of degree into differences of kind, and making antitheses 

 between overlapping groups, partakes not a little of the 

 ludicrous. 



We seem to be confronted by a dilemma ; for the group, 

 as a whole, is too unwieldy to grasp, while the average, 

 though convenient, is treacherous. What we should like 

 is some picture or measure of the distribution of a given 

 trait throughout the members of a group ; and, fortunately, 

 such measures and pictures can be had. Convenient and 

 compact measures of variability are afforded by the science 

 of statistics, and are of no less importance than the 

 average ; but still better, because closer to the actual 

 facts, are graphic or tabular pictures of the distribution 

 of the trait, showing the frequency with which it occurs 

 in each degree. The distribution of a trait is for some 

 purposes more important than the average. 



After considering certain precautions and criticisms, Prof. 

 Woodworth dealt in order with the various senses. The 

 point of special interest is. he pointed out, as to whether 

 the statements of many travellers, ascribing to the 

 " savage " extraordinary powers of vision, hearing, and 

 smell, can be substantiated by exact tests. The common 

 opinion, based on such reports, is, or has been, that 

 savages are gifted with sensory powers quite beyond any- 

 thing of which the European is capable, though Spencer 

 explains that this is a cause of inferiority rather than the 

 reverse, because the savage is thus led to rely wholly on 

 his keen senses, and to devote his whole attention to sense 

 impressions, to the neglect and atrophy of his intellectual 

 powers. 



Sight, hearing, smell, touch, the pain sense were each 

 considered in detail, and Prof. Woodw-orth came to the 

 conclusion that, on the whole, the keenness of the senses 

 seems to be about on a par in the various races of man- 

 kind. Differences exist among the members of any race, 

 and it is not improbable that differences exist between 

 the averages of certain grouos. especially when these are 

 small, isolated, and much inbred. Some interest, said 



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