INFLUENCE OF TEMPERATURE 93 



late the data thus obtained and plot results of observations on 

 the following points : I . Percentage of germinations of the con- 

 tinuously heated seeds at the different temperatures. 2. Per- 

 centage of germinations of freshly treated seeds. 3. Comparison 

 with first control lot. 4. Fatal temperature of the untreated 

 seeds. 5. Fatal temperature of the acclimatized seeds. 



144. Relation of Water Content to Endurance of High Tempera- 

 ture. Select 100 plump seeds of corn or wheat. Plant ten in a 

 germinator and grow. Place 50 in a small dish of water and 

 after 12 hours set in incubator at 30 C. for 12 hours. Place 12 

 in germinator. Raise temperature to 40 C. for 12 hours and put 

 in ten untreated seeds. Take out fresh lot and ten old seeds and 

 germinate. Repeat at 45 C. and 50 C. Tabulate results as in 



FIG. 41. Stage for exposure of mounted objects to different temperatures. A, A', 

 screws for clamping to stage of microscope. B, outlet tube. B'> inlet connecting 

 with vessel containing water heated by a flame. C, condenser to illuminate object. 

 A thermometer is set horizontally in the stage near the outer edge. 



the previous experiment, and determine same points, noting also in 

 addition the lessened resistance of saturated seeds. Compare the 

 acclimatization results. 1 



145. Influence of Temperature upon Movement of Protoplasm. 

 Mount a hair of Trade scantia or some convenient cell on a glass 

 slip and place on a Reichert warm stage, or some other conve- 

 nient form of apparatus on the stage of a microscope, and measure 

 rate of movement of granules in a strand of cytoplasm by means 



1 Just, L. Ueber die Einwirkung hoheren Temperaturen auf die Erhaltung der 

 Keimfahigkeit der Samen. Cohn's Beit. z. Biol. d. Pflanzen. 2: 311. 1877. See 

 also, Kindsel, W., in Landw. Versuchssta. , 54 : 134. 19- 



