228 



HEAT AND PROTOPLASM 



[Ch. VIII 



movements of Vertebrate cilia lies between 35° and 40° C, 

 and that a gradual elevation of temperature to this point is 

 accompanied by gradual increase in the rapidity of the stroke, 

 the law of which is exhibited in the curves shown in Figs. 69 

 and 70. 



This variation in rate and regularity of cilia movement with 

 change in heat is marked in Infusoria, as Rossbach ('72, p. 312) 



80 



70 



60 



50 



40 



30 



20 



10 



80 



70 



GO 



50 



40 



30 



20 



10 



O' 10' 20' 30' 40' 



Fig. 69. — Curves showing relation between temperature (curve Tr) and rapidity 

 of movement of the cilia of the mouth and oesophagus of the frog. The abscissse 

 give, in minutes, the lapse of time from the beginning of the experiment. The 

 ordinates give, for the temperature curve, the degrees Centigrade, and, for the 

 other curve, the corresponding number of units of motor activity for the imme- 

 diately preceding 2 minutes as registered by Engelmann's apparatus. (From 

 Engelmann, 77.) 



and ScHUEMAYEK ('90, pp. 411, 412) have shown. The lower 

 the temperature falls below 15° C, the slower the locomotion, 

 almost ceasing at + 4°. Upon raising the temperature above 

 15°, motion quickens, until, between 25° and 30°, motion 

 reaches a maximum, the Ciliata shooting back and forth with 

 the quickness of an arrow. Between 30° and 35°, the move- 

 ments become still more violent, and take on a new character. 

 They are no longer coordinated. Towards 40°, the progres- 



