121 



Page. 

 §5, Expérimental object 21 



Coleoptiles of Avena sativa. Advantages and dis- 

 advantages of the object. Tho growing of the 

 object. 



§6. Apparatusanddarkroom 25 



The thermostat. Eequirements. Shutting; 

 Stirring-apparatus ; Heating ; Accuracy ; Venti- 

 lation ; Humidity; Rotating axle ; the thermo- 

 regulator. 

 The dark room. Ventilation. Heating. Humidity. 



§7. Sources of error 31 



A. Sources of error due to the expérimental 

 object. Individual variability. Nutations, 

 Height, âge, position and preliminary treat- 

 ment of plants used. 



B. Sources of error caused by expérimental 

 conditions. Purity of the atmosphère. Tem- 

 pérature. Humidity. Light used. 



C. Sources of error due to the observer. 

 Personal error. 



CHAPTER H. RESULTS 46 



§ 8. The presentation-time at différent tem- 

 pératures 46 



Explanation of tables. Tables for 0° 0.-40° C. 



§9. Summary of results 54 



Table giving summary of presentation-times at 

 différent températures. Discussion of this table. 

 Explanation of plates IV and V. 

 4? 10. Summary and discussion of reaction- 



times 61 



Reaction-time no spécial object of this investi- 

 gation. 

 Way in which the reaction-time was determined. 



