§2] EFFECT ON GENERAL FUNCTIONS 227 



represent temperatures (Centigrade) from 0° on the left to 44° 

 on the right. The rate of movement increases regularly up 

 to a maximum (the optimum), a rise of 1° C. being associated 

 with an increased rate of movement in Chara of 1.4 mm. ; in 

 Vallisneria of 0.62 mm. ; in Elodea of 0.26 mm. The rate of 

 increase is, in general, slightly greater near the optimum. 

 The optimum varies, in the three species, from 34° to 39°. 

 Beyond the optimum the rate rapidly decreases, cessation of 

 movement being reached, in the case of Elodea, in 8.7°, in 

 Vallisneria in 6.2°, in Chara in 8.4° beyond the optimum. 

 The curves exhibited in Fig. 68 are characteristic of other 

 vital functions besides motion, and illustrate this general law, 

 that the optimum temperature for the vital activities lies 

 much nearer to the maximum vital temperature than to the 

 minimum. 



After having seen that the rate of flow of protoplasm is 

 dependent upon temperature, we should expect to find, as we 

 do, that that other form of protoplasmic motion, cilia vibration, 

 would be likewise dependent. Some quantitative data con- 

 cerning relation of temperature and rate of vibration were 

 gained as early as 1858 by Callibtjeces. He placed a bit of 

 ciliated membrane from the frog's oesophagus in a moist cham- 

 ber, and in contact with the cilia he laid a small glass cylinder, 

 horizontally supported, and provided with a dial by which its 

 revolutions could be counted. He found that the mean time 

 for a revolution was, — 



at 12° to 19° C. . . .22 minutes, 3 seconds ; 



at 28° C. .... 3 minutes, 7 seconds ; 



thus, in increasing the temperature from 15° to 28° C, the rate 

 of vibration is increased sevenfold. 



Essentially similar results were obtained, through the use of 

 new methods, by Roth ('66, pp. 185-189), upon the ciliated 

 epithelium of the frog's uterus, rabbit's trachea, and gill of 

 Anodonta, and by Engelmann ('68, pp. 381-884 ; 443, 444 ; 

 454, 455 ; and '77), upon the frog's oesophagus. The simplest 

 of these methods was to determine the rate of the transportation 

 of fine particles over the surface of the tissue. The result of 

 these studies showed that the optimum temperature for the 



