VELOCITY OF REACTION. HETEROGENEOUS SYSTEMS 139 



the Pacific terrapin (Clemmys mamorata), according to ob- 

 servations of Charles Snyder. 1 His observations give the 

 following values for the number of heart-beats in one 

 minute : 



Temp. o 2.5 5 10 15 20 25 30 35 37.5 40 



Number 0.75 3.2 4.9 7.8 9.7 20.7 27.3 46 48.6 48.2 43.3 

 Do. calc. 2.4 3.2 4.2 7.0 11.4 18.5 29.3 46 71 87.7 106 



/-i is found to be 16,060. As is seen from the figures, the 

 action of the heart has an optimum. This circumstance 

 probably depends upon changes in the protoplasms near 

 o and 50 ; in the latter case coagulation occurs. 2 There- 

 fore the calculated values coincide with the observed ones 

 only within a certain interval, 2.5-30 degrees. The rapid 

 increase in the neighbourhood of the freezing point is very 

 similar to that found for the two other phenomena of life 

 studied above. 



Another process of great practical importance caused 

 by living cells is the production of alcohol and carbonic 

 acid from glucose by yeast plants. This process has been 

 investigated very thoroughly by Aberson. 3 He found that 

 the formula of Henri is valid for this reaction, as will be 

 seen from the following figures, in which the quantity of 

 glucose (A x) was determined by means of a polarimeter. 

 A is the beginning concentration, A ^rthe corresponding 

 quantity after / minutes. The temperature was for the 

 first series 17.5, for the second 27 C. 



1 Charles D. Snyder : University of California Publications, Physiology, 2. 

 125 (1905). 



2 Loeb : Vorlesungen uber die Dynamik der Lebenserscheinungen, p. 155 

 (1906). 



8 Aberson: Rec. d, tray. chim. /. Pays-Bas et de la Belgique, 22. 78 (1903), 



