( ;57s i 



per cent (•(' llio same into Wcii/idiiic. At ;i liiulicr tcniix'ratiirc llic 

 |»f(i|Kii-ti()ii i^ aiiotlicr. tur in lour ('X|»(M-iin('iits with oiic-tcntli iioi-iiial 

 li\ (Iroclilofic acid. iiitfic acid. sidpliiific acid and livdfoUfoniic acid 

 llic |ii-(»|i()rtioiis at a 100 wci-c i-cs|»ccti\('lv ()t).4. ()7..'). ()3.1 ajid 

 ()5.<S |)('f cent. tliei'croi-('. niucli lowci'. 



To uci some data rcspcctinu- the x'clocitv ot" fcaction a hcakcf w itli 

 50 |)ef cent alcohol which contained hvdi-ochloi-ic acid in lejith- 

 iiofnial concent fation was ])ut iiHo a thei-niostat and \vhile sliri'inu' 

 N'iolenth aii<l |)assiim- a cnn-ent ot' cai'hon dioxide o\ei' the surface 

 a few' U'fanis of' hvdi-a/ohen/.ene w cfe introduced into the li(|uid in 

 which that sidtstance is hut litth' soluhh'. 



At 25, the \(docilv a|)|»eai'ed to he dependent on the conciMitration 

 of llie acid and it increased more rapidlv tliaii the concentration. 

 Tlio experiments are hein.u' contiinu'd in the two (hreclions indicated 

 altoN'e. 



(('hem. I. ah. I'liixcrs. (//■ou/K/t'u). 



Physiology. "O/i tin' diirdtion of the ron/jH'fisaton/ pr/nsi' after 



siiiitii/tftioii of' till' itiincli' of till' mil III iiialnin heart.'' 1>\' Pi'of. 

 K. l'\ Wf,n('K]:i}A( It. fCommiinicated hy Prof. Pkkklii.vrin(;). 



(('.ommunicated in the meeting of :iO November 1902). 



Wlien an (\xtra-syslole is set \\\) hy ai'titiciai sliniidiifioji of the 

 ventricle or auricle of the heatiiiii' frog's lieart, this oxtra-syslole is 

 followed up hy a pause longer than the i)auso succeeding a spon- 

 taneous systole. This long interval was studied hv Marey, Dastkk 

 and others, and called a c(tnii)ensatorv pause, because the longer 

 quiescence of the heart was regarded as a compensation for tlie extra 

 acti\ily of llie heart muscle. And it was not witliout reason that 

 the word '^conij>ensation'" was used, because tlie j)anse after an extra- 

 svslole is of such leuglh, that tlie folh)wing spontaneous contraction 

 just commences in the moment when it would iiave set in if, ijistead 

 of i\\\ extra, a spontaneous systole hiid preceded. Exgelmanx (6) 

 has given a simple and exhaustive explanation of the pause: the 

 normal, physiological stimubis to contraction reaching the heart from 

 the vena cava and causing it to contract finds, after an extra-systole 

 auricle and ventriide iti a refractory phase and so it cannot cause 

 a contraction, it is only the following stimulus which tinds the 

 heart again in a condition in which it can react on that stimulus; 

 the contraction (the "jxisl com|>ejisatoi-y'") then commencing, [»resents 



