NA TURE 



[April 6, 1905 



formations are further removed from their physio- 

 logical correlates (than the psychical elements), and 

 this removal is greater the more complex the 

 psychical compounds become. And it is just at 

 this point that psychology as an independent science 

 in the proper sense of the word takes up its task." 

 That is to sa\-, it is the task of psycho-physics to dis- 

 criminate the elements of our psychical processes and 

 to discover their physiological correlates, but it is the 

 task of psychology proper to discover the purely psy- 

 chical laws of the synthesis of these elements — a task 

 which would remain to be carried out, though the 

 workings of the brain " stood as clearly exposed to 

 our eyes as the mechanism of a watch." 



Wundt then formulates four such fundamental 

 psychical laws or principles, of which the first and most 

 important is the " principle of creative resultants," the 

 principle " that the product arising from any number 

 of psychical elements is more than the sum of those 

 elements .... it is a new formation incomparable in 

 all its essential attributes with the factors that con- 

 tribute towards it." So "a clang is more than the 

 sum of its partial tones." " In the same way every 

 spatial percept is a product in which certain elements 

 (the local signs) have yielded up their independence to 

 impart to the product an entirely new property, 

 namely, the spatial ordering of the sensations. 

 In binocular vision the separate images of the 

 two organs of vision disappear, to give rise in 

 the common resultant image to the immediate per- 

 ception of solidity and depth." On the other hand, 

 the neural correlates of these elements remain a 

 spatially ordered manifold, exhibiting no corresponding 

 fusion or synthesis. The acceptance of this principle 

 is of the first importance for the progress of physio- 

 logical psychology, but whether it is compatible with 

 adhesion to the doctrine of psycho-physical parallelism, 

 as Wundt maintains, may be seriously questioned, 

 as also whether it can properly be called a principle 

 of psychical causation. It seems clear that if with 

 Wundt we recognise this and the other psychical laws 

 that he formulates, whether or not we admit them 

 as principles of psychical causation, we cannot main- 

 tain the principle of psycho-physical parallelism in 

 the rigid form in which it is so widely current at the 

 present time. 



It is a pleasure to welcome the appearance of the 

 first part of an English translation of this great work. 

 Prof. Titchener has accomplished this part of his 

 difficult task with all the care and skill which his 

 previous labours in this line have prepared us to expect. 



In spite of the title of this work, it is as much a 

 treatise on experimental as on physiological 

 psychology', and in view of the common misconcep- 

 tions of the relations of experimental to other methods 

 in psychology the following quotation may fitly con- 

 clude this brief notice : — " We now understand by ' ex- 

 perimental psychology ' not simply those portions of 

 psychology which are directly accessible to experiment, 

 but the whole of individual psychology. For all such 

 psychology employs the experimental method : 

 directly, where its direct use is possible ; but in all 

 other cases indirectly, by availing itself of the general 

 NO. 1849, VOL. 71] 



results which the direct employment of the method 

 has yielded, and of the refinement of psychological 

 observation which their emplovment induces." 



W. McD. 



RADIUM AND RADIO-ACTIVITY. 

 Radium Explained. By Dr. W. Hampson, M.A. 

 (Jack's Scientific Series.) Pp. x+122. (Edinburgh 

 and London : T. C. and E. C. Jack, ic)05-) Price 

 IS. net. 



THIS little bool<, which is sold for the modest 

 price of one shilling, will, we think, serve a 

 useful purpose in giving an elementary acquaintance 

 with the subject of radio-activity, so far as that is 

 accessible to those with little scientific knowledge. 

 The explanations given of the experimental properties 

 of radium are, so far as we have observed, clear and 

 accurate, and the get-up of the book, though not 

 superb, is respectable. Probably one of the most 

 valuable chapters in the book is that on the medical 

 aspects of radium, and its possible uses in the cure 

 of disease, for few writers on radio-activity generally 

 are competent to discuss this part of the subject. Dr. 

 Hampson is of opinion that the medicinal value of 

 mineral waters is connected with their radio-activity. 

 This question, we think, should easily be susceptible of 

 a definite and conclusive answer. There would not be 

 the slightest difficulty in giving baths of weak radium 

 solution more potent by far than the richest mineral 

 waters. Why not test the medicinal value of these '' 

 It is really urgent that this experiment should be tried 

 by competent hands. 



It is, we think, to be regretted that Dr. Hampson 

 has plunged into an attack on modern views of the 

 constitution of matter, as expounded by Prof. J. J. 

 Thomson, Sir Oliver Lodge, and others. We have read 

 these criticisms with the attention due to a worker 

 like Dr. Hampson, who has done good service in the 

 cause of science, but cannot admit that they possess 

 any validity. To go fully into the questions which 

 he raises would take us beyond the limits of this 

 notice, but we may briefly discuss one or two of the 

 points. At the outset, Dr. Hampson objects to the 

 definition of mass by means of inertia. Mass, he 

 says, is quantity of matter ; inertia is dependent on 

 velocity as well as on mass. 



It is true, no doubt, that the definition of mass 

 as quantity of matter may be found in some old- 

 fashioned text-books of repute. But such a defini- 

 tion has no value, for how is the quantity of 

 matter to be ascertained? The choice practically 

 lies between defining mass by inertia at a given speed 

 or bv gravity. So far as is known, exactly the same 

 ratio between two masses of ordinary matter will 

 result, whichever method of comparison is adopted. 

 .As, however, gravity depends on local circumstances, 

 while inertia (at given velocity) does not, the latter 

 property is preferred for the definition of mass, as 

 being more fundamental. 



No doubt, before it can be granted that the electron 

 theorv fully accounts for the observed properties of 

 matter, it will be necessary to show that it will explain 

 the phenomena of gravitation. This, at present, it 



