Light in Greenhouse Culture 6i 



greater height and exhibited more sensitiveness than 

 those in the white house. The sensitive plants in 

 the green hothouse made a little headway at first 

 and then came to a standstill. In the hothouse 

 with the blue glass practically no headway was 

 made. In comparing the weight of the plants in the 

 various hothouses with that of the height as previ- 

 ously mentioned, the results will be found to be 

 different. This is clearly seen in Table 9. 



Table 9 



Hothouse 



Weight of 

 Stems and 

 Leaves 



Weight of 

 Average 

 Leaf 



Diameter 

 of 

 Stem 



White 



Grams 

 8.400 



Grams 

 0.600 



Mm. 

 30 



Red 



4.600 



0.250 



2.0 





0.300 



0.150 



1.5 



Blue 



0.150 



0.095 



1.0 





It is very curious to find that the plants in the 

 red hothouse, although the highest, were not the 

 heaviest. The weight was almost double in the 

 white hothouse, although in height the plants did 

 not compare to those in the red hothouse. 



Experiments on lettuce, similar to those on the 

 sensitive plants, yielded like results. Lettuce grown 

 in the white hothouse produced large thick . leaves 

 with well rounded heads, in fact the plants here 

 did not differ from those grown in the open. Let- 

 tuce grown in the red house was drawn, its leaves 



