Fig. 2. — Tomato plants, showing coloured roots grown in dry air of the 

 greenhouse, after treatment with lanolin preparations of the growth sub- 

 stances. There are roots on the long stem-like leaf-stalks bending towards 

 the camera, as well as on the true stems. The bending of the stems arose 

 from the treatment on one side. The photographs were taken i8 days after 

 treatment. Left: Leaf and one side of the stem above it, smeared with 0.50 

 per cent, a-naphthalene-acetic acid. 

 Right: Similar plant treated with i.o per cent, ethyl a-naphthalene-acetate. 



