232 HEAT AND PROTOPLASM [Cn. VIII 



dition ( u Scheintodtenstarre ") from which it might return to 

 a normal condition of sensitiveness. Such a rigid state was 

 brought about by subjecting a decapitated frog in water to 

 35 II. (43.8 C.) for 1 minute. I will now add some additional 

 cases of production of temporary heat-rigor in protoplasm which 

 I have found in the literature. 



In 1863, MAX SCHULTZE (pp. 33, 34) found temporary heat-rigor in 

 Actinophrys, which retracts its pseudopodia and appears as a lifeless mass 

 at 35 to 38, but is not killed until 43 is reached. In the same year SACHS 

 ('63, p. 453) repeated more fully the experiments of P. DE CANDOLLE on 

 Mimosa pudica. He found that a temperature of 30 C. for 3 hours did not 

 produce rigor. A temperature of 40 for 1 hour produced loss of sensibility 

 during 20 minutes. Raised slowly even to 50, sensibility was only tempo- 

 rarily lost, but 52 proved fatal. Immersed in water, heat-rigor occurred 

 at a temperature 5 to 10 lower. SACHS clearly distinguishes a "voriiber- 

 gehende Wiirmestarre " from death. 



KUHNE ('64, pp. 45, 67, 87, 103) drew a sharp contrast between the 

 rigidity of death, which he calls " Wiirmestarre," and the transitory immobile 

 condition or " Warmetetanus." He found this latter condition to occur in 

 Amoeba subjected to 35 for 1 minute, in Actinophrys subjected to 35-40 

 for several minutes, in motile Myxomycetes (Didymium serpula) subjected 

 to 30 for 5 minutes, in Tradescantia stamen hairs at over 45, when gradu- 

 ally brought to that temperature. In all cases there is such a relation 

 between temperature and time of subjection that the greater the one is the 

 less need be the other in order to produce heat-rigor. 



Very instructive also are the observations of HOFMEISTER ('67, pp. 54, 

 55) which I briefly summarize : Hairs from the stem and leaf of Ecbalium 

 ageste showing lively movement were gradually raised from 16-17 C. to 

 40 C. They became motionless at 40 C. After 1 to 2 hours, movement 

 returned, and was very violent. Cooled and raised again to 45 C., the proto- 

 plasm was motionless at first, but after 17 minutes movements recurred but 

 were not rapid. Put again into 47.5 (after first cooling) heat-rigor occurred 

 in 5 minutes, but upon cooling, movements return. 



Very similar experiences have befallen subsequent investiga- 

 tions which unite in supporting the conclusion that at a certain 

 temperature, slightly below the death point, protoplasm becomes 

 immobile, but retains the capacity for subsequent reacquisition 

 of movement upon lowering the temperature. 



Finally, studies upon muscle, especially those of CHMULE- 

 VITCH ('69), SAMKOWY ('74), MORIGGIA ('91), GOTSCHLICH 

 ('93), and others, have shown that as the temperature is ele- 

 vated up to about 30 C., the muscle contracts more and more, 



