62 Diseases of Greenhouse Crops 



long, straight, blanched and drooping. Those 

 grown in the hothouse with green glass made a slight 

 growth, but the leaves were more curled than those 

 in the red house. In the blue hothouse, the lettuce 

 plants added only a few leaves, without increasing 

 the height attained in the first two weeks (fig. 9, 

 i-j.). 



Experiments on peas and beans yielded similar 

 results. In both plants the normal and most vigor- 

 ous growth was found to occur in the white hot- 

 house. The plants in the red hothouse were taller 

 but thinner, while in the blue hothouse the minimum 

 of growth occurred. The beans bloomed and fruited 

 equally well in the white and in the red hothouses. 

 In the green and in the blue houses the plants soon 

 died. With the peas, blooming and fruiting seemed 

 to be normal both in the white and in the red hot- 

 houses. In the house with the green glass, the peas 

 remained in bloom for three weeks, but did not 

 fruit. In the blue house, the peas failed to bloom 

 altogether. 



Experiments with ornamental plants, such as 

 Coleus, yielded similar results. The Coleus in the 

 white hothouse produced a normal well developed 

 plant. In the red house there was an increase in 

 height with a decrease in foliage. In the green 

 and blue hothouses there was very little develop- 

 ment (fig. 9, a-h.). 



