46 



of plants was observed in the light of the small red 

 electric lamp used for reading the thermometer, and 

 immediately afterwards the same set was placed near the 

 lamp under the glass-bell, (which gave a much stronger 

 light). In the flrst position I noted down 50 o/o curved, and 

 in the second one nearly 100 o/o. That this was not a 

 Personal error, was shown by the fact that two other 

 persons who tested in the same way, also found the 

 seedlings curved with the aid of the saffranin-lamp to be 

 twice as many as by the smaller lamp. 



C. Sources of error due to the observer. 



The Personal error only belongs to this heading and 

 it is a constant one and therefore left out of considération. 

 It cannot be very great either, as my figures are perfectly 

 in harmony with those of Mrs. Rutten — Pekelharing. 



A further small error may be introduced by the fatigue 

 of the eye, but the errors caused by this can never be 

 more than magnitudes of the second order. 



CHAPTER IL 



RESULT3. 



§8, The présent a tion-time at différent 

 températures. 



After ail that has been said in the preceding chapter I 

 need not give further space to the methodical part ofthe 

 investigation. A few remarks only hâve to be made before 

 giving a survey of the ligures obtained at différent tem- 

 pératures. 



As has been set forth in § 4, the results of the esperi- 

 ments at a deflnite température and with a definite time 

 of preliminary warming were collected into one table. 



