370 SECTIONAL TRANSACTIONS.— I. 



dissociation curve. In other words, for a given increase in carbon dioxide pressure, the 

 carbon dioxide content of the blood increased to a lesser extent than in the bloods of 

 normal individuals. This indicated a deficiency of the buffering power of the blood, 

 which, on further investigation, appeared to be due to an alteration of the normal 

 ionic interchange between plasma and corpuscles. In addition, it was found that the 

 clotting deficiency in haemophilics seems to be due partly to an alteration in the 

 permeability of the blood cells. 



Prof. K. J. S. McDowall— The Effect of Mental Stress on Man. 



Of recent years a large amount of evidence has been accumulated regarding the 

 effect of mental stress on man. Briefly, it may be stated that the general effect of 

 such stress appears to be identical with that produced by exercise, and appears to be 

 associated with general increased sympathetic activity which is specially well seen in 

 the modification of the activity of the circulation and of the alimentary canal. In 

 relation to the former, it becomes evident that there is an increased rate of the heart 

 and vasomotor tone which together bring about a great increase in blood pressure. 

 Small degrees of mental effort which even to the individual may appear insignificant 

 can be shown to cause definite constriction of the blood vessels of the skin, and all 

 degrees are found between this and the rapid cardiac action of which the individual 

 is conscious. 



In physical or mental stress there is now definite evidence that alimentary activity 

 in general is reduced. Salivary and gastric secretion is markedly reduced, while there 

 is marked delay in the emptying of the stomach. There is good reason to believe 

 that such conditions may be largely responsible for many abmentary ailments, and 

 may in part be responsible for undue strain on the circulation. 



Dr. R. H. Thouless. — The Physics oj the Psycho-Galvanic-Reflex Phenomenon. 



The electrical changes in the body which result from the physiological con- 

 comitants of emotion have been stated to be : — 



(a) A change in resistance. 



(b) A change in the back E.M.F. of polarisation. 



(c) A change in the difference between the potential of the skin at the two 



points to which electrodes are applied. 



There has been a tendency for physiological investigators (Gildemeister, Prideaux, 

 Sidis, &c.) to assume that only one of these changes really takes place, and that other 

 investigators' reports of other changes are due to carelessness in interpretation of 

 results or even to ' errors in logic ' (Sidis). 



Experimentation under different conditions of circuit shows that all three changes 

 take place. The change in resistance is an increase immediately after the stimulus, 

 followed by a larger decrease after a latent period of about 1-8 seconds. The change 

 (c) has two forms. Sometimes it is a simple increase of the somatic current. At other 

 times a very small increase is followed by a larger decrease, which is followed again by 

 a still larger increase with very slow recovery. There is also a change in the polarisa- 

 tion produced by an external current, but this may simply be the secondary effect of 

 the change in bodily resistance. 



The electrical changes in the body produced by emotion are .thus more complex 

 than has generally been recognised by those who have proposed physiological explana- 

 tions of them. An adequate physiological explanation of the phenomena must take 

 into account the three changes in the somatic current which correspond probably to 

 three different physiological events. 



Prof. H. E. Roaf. — The Effect of one Coloured Light on another with 

 reference to Theories of Colour-vision. 



Dr. F. W. Edridge-Green, C.B.E. — The First Recorded Cases of Colour- 

 Blindness. 



It is usually stated that the first definite record we possess of a case of colour- 

 blindness is Huddart's account of the shoemaker, Harris, in 1777, but that great 

 genius, Robert Boyle, in his ' Some Uncommon Observations about Vitiated Sight,' 

 1688, gives an account of two cases. The first case is that of a girl of about eighteen 



