ON MENTAL AND MUSCULAR FATIGUE. 297 



Method. — Pencil dot is made in each square. Across every tenth 

 square a diagonal is drawn. Unit effort is ten squares. Number of 

 units marked noted per period. 



Test C. — Multiplication sums. Five digit numbers multiplied by 

 two digit numbers. Thirty minutes a day for two days. Given at 

 conclusion of school working day. In each of these tests a signal was 

 given at the end of each five-minute period in order that the output 

 per period might be calculated. 



Test D. — Dotting test. The machine which is being used is Dr. 

 Rivers' modification of Dr. Dougall's apparatus. 



The Committee hope to produce tbeir report in December. 



Body Metabolism in Cancer. — Report of the Committee, consisting of 

 Professor C. S. Sherrington (Chairman) and Dr. S. M. Copeman 

 (Secretary). 



Consideration of the curves of cancer mortality in the human subject, 

 whether male or female, discloses the interesting and important fact 

 that cancer is not, as is usually thought to be the case, a disease of old 

 age, however much it may be related to senescence of certain of the 

 body tissues. As a matter of fact, the disease is of extreme rarity in 

 the later years of life, especially in the female sex. Thus the charac- 

 teristic feature of the age incidence of cancer, as pointed out by Eoger 

 Williams and others, and as demonstrated by the returns of the 

 Registrar-General, is not its continued increase with advance of years, 

 but rather its disproportionate augmentation in the post-meridian periods 

 of life — i.e., between the ages of forty-five and sixty-five years — liability 

 to the malady waxing as the reproductive activities wane. The facts, 

 indeed, clearly show that cancer is not a disease of senility merely, 

 which per se plays no part in its development. 



In the animal world the age incidence of cancer is evidently governed 

 by a similar law, as has been demonstrated by Strieker for horses and 

 dogs, and by Bashford and Murray for mice; all these observers being 

 in agreement as to the rarity of malignant tumours in early life and 

 their relative frequency in later life, antecedent, however, to onset of 

 old age. 



In the light of these facts it would seem not improbable that the 

 onset of malignant disease, whether in man or the lower animals, may 

 have intimate relationship with diminished or perverted functioning of 

 the reproductive organs, which, under normal circumstances, may be 

 regarded as exerting — possibly by virtue of their so-called ' Internal 

 secretions ' — some restraining and co-ordinating influence on the 

 growth of the somatic tissue elements. 



Evidence of the existence of such a controlling influence is found in 

 the fact, on which there is now general agreement among those engaged 

 in the experimental investigation of cancer, that whereas transplanta- 

 tion of ' spontaneous ' cancer in the mouse to normal individuals is 

 apt to prove successful in but few instances when full-grown animals 

 are employed for experimental purposes, complete insertion success has 



