4 Dr. Gardner on the Action of Yellow 



August 14th. — The same plants, with the addition of a fresh 

 crop F in the green ray. Exposure from 9 a.m. to 3 p.m. 

 to 6 hours' sunshine. Temperature in shade, noon, 85° Fahr. 

 and 105° in the sun. Result at 3 p.m. 



The leaves of A and B were developed. Experiment con- 

 cluded after 30 hours, of which 12^ were sunshine and 17| 

 darkness. The greater altitude of the plants in the indigo 

 and violet rays is due to the slowness of exhalation by vege- 

 tables in those colours, an effect, not of light, but of heat. In 

 this instance no effect whatever was produced on the original 

 yellow colour of the seedlings in the indigo and violet light, 



10. The subjoined table contains the comparable points of 

 six similar experiments. The first column gives the number 

 of the experiment; the second the plants used; the third the 

 number of hours of sunshine; fourth, the whole duration of 

 the experiment; and from the fifth to the thirteenth column, 

 the rays of the spectrum ; the figures placed in the last spaces 

 indicate only the order of colour in the particular observation. 

 The sign of minus is introduced whenever the effect of the ray 

 was not tested, or the result was defective. 



Table showing the active and inactive rays of the spectrum 

 in producing the green colour of plants. 



Plants. 



Turneps 



Beans, &c. .. 

 Turneps, &c. 



Turneps 



Turneps 



Turneps 



22 

 14 



8 

 23 

 17-5 



5-5 



109 

 95 

 69 



101 



52 



6 



Active rays. 



Inactive rays. 







In experiment 5 the blue ray produced a green colour, but 

 the usual effect was a light olive. The indigo, violet and la- 

 did not become green, and therefore the value is negative; but there was 

 a visible alteration, designated olive, and indicating the tint which vegetables 

 assume in passing from the yellow colour, produced in darkness, to green. 



