§2] 



EFFECT OX GENERAL FUNCTIONS 



225 



DEGREES 

 1 3 5 7 9 11 :3 15 17 19 SI 23 £5 27 g9 31 i 



temperature and interval between contractions is given in 

 Fig. 67. We cannot say that the increment of excretion is 

 exactly equal to that of con- 

 traction, but there is doubtless 

 a correlation between the two 

 activities. 



From all these facts we may 

 conclude that, within certain 

 limits, an increase of tempera- 

 ture increases metabolism, and 

 a diminution of temperature 

 diminishes it. But the incre- 

 ment in metabolic processes 

 soon finds a limit at a tem- 

 perature above which the 

 metabolic processes begin to 

 diminish. 



2. Effect of Heat upon the 

 Movement of Protoplasm and 

 its Irritability. — All observers 

 (DUTROCHET, '37, pp. 777, 

 778; Nageli, '60, p. 77; 

 Sachs, '64 ; Hopmbistek, '67, 

 pp. 53, 54 ; and Cohn, '71, for 

 plant cells; and KiJHNE, '59, 

 p. 821 ; and SoHTJLTZE, '63, 

 p. 46, for Protozoa) agree 

 that a gradual increase in 

 temperature above that of the 

 ordinary living room results, 

 within certain limits, in an 



Fig. 67. — The mean thermal carves de- 

 termined by EossEACH for the con- 

 tractile vesicle of Infusoria. I, for 

 Euplotes charon ; II, for Stylonychia 

 pustulata; III, for Chilodon cucnl- 

 lulus. The abscissae indicate degrees 

 of temperature. Centigrade, in two- 

 degree intervals ; the ordinates give 

 the number of seconds elapsing 

 between successive contractions of 

 the vesicle, in two-second intervals. 

 (From Sempek, "Animal Life.") 



increase in the rate of movement of the protoplasm. A 

 diminution in temperature, on the contrary, causes a decrease 

 in the movement. 



For this acceleration with increased temperature, Nageli 

 sought to obtain a quantitative expression. He measured 

 the time consumed at different temperatures in the migration 

 through 0.1 mm. of the granules floating in the stream of 

 protoplasm seen in the end cells of Nitella syncarpa. Some 



