36 ORGANISM AND ENVIRONMENT 



recired to keep up the work. These considerations 

 ledne to the conchision that it is probably in virtue 

 of s acidity that dissolved COo (H2CO3 or carbonic 

 aci) affects the respiratory centre, and that other 

 acis will therefore have a similar effect, and will tb 

 he^ CO2 to excite the centre. This theory ^^" ' 

 wb less COo in the alveolar air is sufficient 

 bnthing under the various conditions ji 



to. 



X the time, however, there was no n 

 ofLCCurately measuring the slight : 

 bled. The old method of adding 

 anndicator changed colour wa? '^ 

 bualso fallacious in principle, 

 sliatly alkaline, yet quite a lar 

 bedded to it before it beconi 

 caid "buft'er substances," wl 

 bing with acids or alkalic 

 ve' definitely acid or alk: 

 aci which has to be ad 

 rertion is a measure of 

 tha of the alkalinity 

 mcern ideas the acif^ 

 detnds on the relativ 

 geiand hydroxyl "ic 

 mtsured directly by 

 diiculties in apply] 

 grit. 



1 1912, howej 

 ceied in obtaii 

 gard publisj 



