30 Leitch . — Some Experiments on the Influence of 
flask was interposed between the beaker and the tap, and for temperatures 
between that of the water and 15 0 the micro-burner was used to heat the 
flask. Between i° and 5 0 ice was used. By these means a complete range 
of temperatures from i° upwards was available. 
The experiments from 15 0 upwards were performed on a table built 
into the ground and therefore free from any danger of disturbance by 
vibration or shaking. At lower temperatures they were carried out in 
a colder room where such an arrangement was not available, but the room 
was a basement one, and repeated tests showed no disturbance by shaking. 
In view of the great amount of trouble to be saved by conducting the 
microscope experiments in daylight, a series of experiments was made to 
test for a possible influence of a sudden transition from dark to light, or as 
Vogt (T 4 ) incidentally records for Lupinus , in his paper on the influence of 
light on growth in Arena, for a possible increase of the rate of growth 
in light. The temperature of about 25 0 was chosen for these experiments 
as giving a high rate of growth likely to show reactions clearly, and as being 
subject to no injurious effect. 
Table A gives the results of these experiments ; the readings are 
half-hour readings, and the numbers micrometer divisions. In Experiments 
3, 7, and 9, a 100-C.P. electric lamp at about fourteen inches was used in 
addition to daylight. 
Table A. 
^ Commencement of light, f Stoppage of light. 
1. i-7, 1 1-7, 2-o, f 1-9, 2-1. 
2 . i-6, >|r i*6, i*6, f i-8. 
3 - i* 5 > i I * 5 ? i- 5 » l ' 5 > f l 'lA l ' 7 > I * 5 > 1 1 * 5 - 
4 . i* 7 , 1 1 * 6 . 
5 * I * 5 > ^ I * 5 * 
6. i*6, \|r 1*7. 
7. i*i» !*4> 
8. i* 5 »l 1-65. 
9. i- 7 , f i* 5 , 1-3. 
The means are, in dark, i*6 ; in light, 1-55. These readings show that, 
neglecting for the moment Experiments 3, 7, and 9, the fluctuations in the 
readings show no constant relation to the presence or absence of light. The 
fluctuation is, indeed, such as takes place in experiments under uniform con- 
ditions. (Compare Experiments 3 and 4 on change of temperature, quoted 
below.) Experiment 9 shows a fall in light, and Experiment 7 a rise 
in darkness after illumination — which results do not necessarily confirm 
each other — and Experiment 3 under the same conditions shows, as the 
experiments in daylight alone do, no influence of the light. 
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