Transactions! of section i. 759 



Hcid its irritability is likewise increased, so that a previously ineffective stimulus 

 is able at once to elicit contractions. Gotschlich has demonstrated that muscle, 

 when sub-minimally stimulated for a period, becomes acid in reaction. Jt is, 

 therefore, believed that the phenomenon of summation of stimuli is not funda- 

 mentally different from the treppe, and is due to the augmenting action of small 

 quantities of fatigue substances. 



4. Influence of Intensity of Stimulus on Reflex Response. 

 By Professor C. S. Sherrington, F.R.S., and Miss S, C. M. Sowton. 



5. Constant Current as an Excitant of Reflex Action. 

 By Professor C, S. Sherrington, F.R.S., and Miss S. C. M. Sowton. 



6. Some Experiments on the Effects of X-rays in Therapeutic Doses on the 

 growing Brains of Rabbits. By Dr. Dawson Turner and Dr. T. G. 

 George. 



The authors spoke of the great importance of the subject, as a full dose of 

 x-rays is frequently administered to children suffering from ringworm ; attempt 

 of the London County Council in March 1909 to make this treatment obligatory. 

 Reference was made to experiments by Recamier and others which showed 

 that the x-rays interfered with the growth of the bones and teeth. The question 

 arose whether any change capable of being observed in the nervous system would 

 be produced by a repetition of such doses of x-rays as are employed in the 

 treatment of ringworm. The experiments of the authors were performed upon 

 young rabbits. One-half of the head was exposed to and one-half protected 

 from an ordinary x-ray dose. This dose was repeated three times, with an 

 interval of a week between each dose. Of six rabbits chosen for the experiments 

 only one survived for examination, so that no corroboration could be obtained 

 of the changes observed. The microscopic changes in the brain were slight 

 and inconclusive, but there were some undeniable gross changes — e.g., the left 

 or unexposed half of the brain was decidedly larger than the right or exposed 

 half ; the iris, first on the left and then on the right side, had undergone fatty 

 degeneration ; all the animals had lost weight during the exposures. It would 

 therefore seem highly desirable that further investigation of this subject should 

 be made. 



7. The Combination of certain Poisons with Cardiac Muscle. 

 By H. M. Vernon, M.A., M.D. 



TortoLse hearts were perfused with oxygenated Ringer's eolation to which 

 known amounts of certain poisons were added. When alcohol, ether and 

 chloroform were used the contraction height of the heart was depressed by a 

 definite amount proportionate to the concentration, and after about ten minutes' 

 poisoning the beats showed no further depression, though poisoning might bo 

 continued for another twenty minutes. On substitution of fresh saline the 

 heart quickly recovered its initial contraction height, at a rate independent of 

 the concentration of the poison used. Also the rate of recovery was about the 

 same for all the three poisons mentioned. Hydrocyanic acid, at considerable 

 dilutions, also depresses the cardiac contractions to a level proportionate to the 

 concentration, but all strengths from C00125 to 001 per cent. HCN produce almost 

 the same effect ; or the effect is not proportionate to the concentration. Greater 

 concentrations still depress the, contractions further, but they permanently injure 

 the heart. It is uncertain -whether sodium iluoride acts like HCN or like 



