The Action of Anaesthetics on Living Tissues. 271 



(4) Kecovery takes place when the vapour is weak (9 per cent, or less), 

 not occurring when the strength is 12 per cent, or more. 



Series III. 



The method adopted in Series II, while suitable for percentages of CHCI3 

 from 1 to 10, is defective in many ways, and an apparatus was designed to 

 deliver a constant high percentage of CHCI3, saturated with water vapour, and 

 at a constant temperature. This consisted of a foot bellows with a branched 

 delivery tube, one limb of which passes to seven Fresenius flasks, the first 

 three containing CHC1 3> the next water, the next two contain a mixture of 

 CHCI3 and water, and the last is empty. The apparatus delivers moist 

 CHCI3 vapour at a concentration of 13 to 17 per cent, (depending on the 

 temperature of the first flask) with a variation in strength of about 

 05 per cent, and a temperature variation of about 0"4° C, and by estimating 

 the strength of the vapour after it has passed through the nerve-chamber, 

 and noting the temperature before and after each experiment, these residual 

 errors can be allowed for. The five flasks on the other limb of the air 

 supply contain water, and a small stream of air passing through them 

 serves to ventilate the other part of the nerve-chamber, thus guarding 

 against accidental escape of CHCI3. A similar apparatus is used for ether : 

 in this case the percentage is about 45. Unless otherwise stated, all further 

 experiments were made with this apparatus, with occasional modifications. 



In this series the strength of the CHC1 3 vapour was 12 - 5 ( + 05 per cent.), 

 and was applied for 10 minutes. The details of the various experiments 

 differed. The values are now absolute, and have been corrected for electrode 

 current. Each ordinate division = 0"002 volt; each abscissa division 

 = 15 seconds. 



In Experiments .108 and 107 (nerves of Frog A) the CHCI3 was applied 

 first to the longitudinal surface and then to the cut end. In Experiment 109 

 (Frog B) the same course was followed, only without making a fresh section, 

 the curve therefore begins close to the zero line. In these three experiments 

 the curves fall at first, the effects being naturally opposite in sign to those in 

 the next three experiments — Nos. Ill, 110, and 117 — where the cut end is 

 first affected. No. 110 is practically a repetition of Series I, No. Ill the 

 same without a fresh section, and No. 117 shows the effect of ether applied 

 for five minutes instead of ten. 



Considering the first half of each experiment — 



(1) CHCI3 (Experiment 111) and ether (Experiment 117) to the distal end 

 of a nerve cause a rise in potential, approximately equal in amount. 



