F. C. Newcombe 
284 
the lentil, or any other seedling, grew always horizontally in the dark, 
how could one ever raise a crop from planted seed? The buried shoot 
would never rise out of the ground. 
Renewed Attempts at Reversal of Geotropic Response 
In the autumn of 1922 the writer planned a series of experiments 
designed to re-examine the question of reversal of geotropic response. 
The most of the experiments were carried through by Miss Anna 
Haire, a skilful graduate student in the University of Michigan. A 
detailed narrative of her work will be published in Scientific Papers 
of the University of Michigan, 3 , to appear early in the year 1924. 
In the present paper only a summary of her work and that of the 
present writer, so far as it relates to the subject in hand, will be 
included. All preparations were kept in temperatures from 21 to 
25 ° C. 
Series I. With vapour of acetic acid. In this series an acid atmo¬ 
sphere was given to the shoots of seedlings. The preparations were 
made in two ways: (1) Seedlings of Pisum sativum L. and Zea 
mais L. (yellow dent) were grown in sphagnum moss till the shoots 
were from 1 to 5 cm. long. The seedlings were then secured to 
wooden bars by means of blotting paper and rubber bands. The 
bars with six to twelve seedlings each were then suspended in damp 
chambers made by lining four-sided glass museum jars with wet 
absorbent paper. The bars extended across the damp chambers and 
were wedged securely in place by pieces of rubber tubing. Thirty- 
three seedlings of Pisum and over 200 seedlings of Zea were used. 
Into each damp chamber, after the seedlings had been inserted, were 
poured 10 c.cm. of 1 per cent, glacial acetic acid, into others the same 
amount of 5 per cent, into others the same amount of 10 per cent., 
and into others the same amount of 20 per cent. acid. The jars stood 
in the dark room with seedlings erect for 5 to 24 hours after receiving 
the acid. This was done to give the acid time to penetrate more or 
less into the cells of the seedling shoots. The jars with 1 per cent, 
and those with 5 per cent, acid received in addition 2 c.cm. of the 
same strength of acid every 12 hours during the period of the ex¬ 
periment. After standing thus for 5 to 24 hours, the jars were turned 
on their side, thus bringing the axis of the seedlings into the horizontal 
position. (2) The other method of preparation was to grow the 
seedlings in the dark room in earth in crystallising dishes 6 cm. in 
diameter. When the shoots were 1 to 5 cm. above ground, the 
crystallising dishes with seedlings undisturbed were wedged into 
four-sided jars, these jars used as culture chambers, and subsequently 
treated in every way as the jars in the first set, that is, acid was 
