THE METABOLISM OF PLANTS. 297 



the amoeboid movements of the plasmodium of Myxomycetes 

 and the rotation of the protoplasm in the cells of the staminal 

 hairs of Tradescantia cease in the absence of oxygen : and 

 finally, it was mentioned in a previous lecture (p. 255), in 

 describing Engelmann's experiments on the .action of light 

 upon the exhalation of oxygen by cells containing chloro- 

 phyll, that it is only when supplied with oxygen that 

 Bacterium Termo is motile. 



On the other hand, just as anaerobiotic plants are capable 

 of growth in the absence of oxygen, so also they are capable 

 of movement. Grossmann and Mayerhausen have observed, 

 for instance, that certain Schizomycetes are motile in the 

 absence of oxygen. 



Further, movement, like growth, is affected by tempera- 

 ture, and in much the same way ; its curve presents the same 

 cardinal points, and it probably bears much the same relation 

 to the curve of respiration as that of growth does. Thus, 

 with regard to the rotation of the protoplasm, Velten found, 

 in the case of Chara fcetida, that the minimum temperature 

 was o C., the optimum temperature, that namely at which 

 the movement was most rapid, was 38'iC., the maximum 

 temperature, that namely at which the movement ceased, was 

 42*8 1 C. ; in the case of Vallisneria spiralis the minimum was 

 o 1 C., the optimum 3875 C, the maximum 45 C. : in the 

 case of Elodea canadensis the cardinal points were oC., 

 36-25 C, and 3875 C. 



In the cells of Chara fragilis Dutrochet detected rotation 

 at o iC., and Cohn in Nitella syncarpa at 2 C. Sachs 

 observed, in the cells of the hairs of Cucurbita Pepo, Solatium 

 Lycopersicum, and of Tradescantia, slow rotation at 12 i6C, 

 rapid rotation at 30 40 C., and slow rotation again at 

 40 50 C. Many other observations might be quoted (Jiir- 

 gensen, Max Schultze, Kiihne), but it is not necessary to do 

 so, for they agree with those which have been given in prov- 

 ing that a rise of temperature from the minimum to the 

 optimum accelerates rotation, and that a further rise from the 

 optimum to the maximum retards and finally arrests it. 

 With regard to amoeboid movement, Kuhne found that the 



