MEDICINE 41 



as a rule, is but little affected. The ray, however, does tend to 

 inhibit the growth of tissues, and Regaud, of the Biological 

 Laboratory of the Radium Institute, Paris, has gone so far as to 

 suggest that radio-sensibility is a property of the nucleus, and 

 is inherent in certain states or temporary states of cell life, the 

 most important being reproduction. Another period of height- 

 ened sensibility, he says, corresponds to the maximum meta- 

 bolic activity of the nucleus in cells which have a secretory 

 function. Thus, radio-sensibility waxes and wanes in the same 

 tissue, at different periods. 



This worker has, therefore, felt himself able to draw up a 

 list of tissues having various degrees of radio-sensibility, and 

 has extended his series to include neoplasms which may also 

 be arranged in order of radio-sensibility. 



An indication of the importance of such a conception was 

 afforded by the well-known fact that spermatogenesis is inhibited 

 by X-rays. In Dr. Bruce's case it would seem that the highly 

 penetrating rays were able to inhibit the activity of the bone 

 marrow, and so produce a failure to create the corpuscular 

 elements of the blood. It is evident that this danger is a very 

 serious one, and that it must be guarded against ; for the 

 tendency of X-ray therapeutics is all towards more rather than 

 less penetrating X-rays. 



The same considerations apply to the use of radium. It 

 is known that the gamma rays of radium are highly penetrating, 

 and several deaths have been reported from pernicious anaemia 

 among workers exposed to radium. Here, also, more light is 

 necessary if we are to enjoy in safety the therapeutic use of the 

 substance. That the penetrating rays do exercise an important 

 influence in checking the growth of cancerous tissues is beyond 

 dispute. The present-day technique of use is, however, evi- 

 dently capable of great improvement. This will scarcely be 

 attained either for X-rays or radium until greater safety to 

 the worker is ensured. As great a thickness as five inches of 

 steel is said now to be insufficient to exclude certain of the more 

 penetrating rays. 



The Nature of Pain. — Medical attention is being focussed 

 more and more on such physiological considerations as the 

 nature and mechanism of pain. Mr. Wilfred Trotter, in Medical 

 Science, recently reviewed the evidence and reached the con- 

 clusion that sensibility to pain is the survival in us of the 

 primordial mode of sensation. He uses the expression " pain 

 nerves," and suggests that they are constantly exposed to a 

 mild " subliminal excitation," the difference between them 

 and all other nerves lying in the fact that they are normally 

 in a state of continuous excitation. When the insulation of 

 nervous tissue, which is very complete in the human body, is 



