PLATE ii 
1. Middle of an intemode of Ricinus communis injected July 18, 1916, with 10 per 
cent malic acid, showing copious surface pith proliferations. The central large nodule 
developed around the needle entrance. Photographed on July 28, 1916. X8. 
2 . —Middle of a Ricinus intemode injected July 18 with 10 per cent uric acid. Sur¬ 
face of pith covered with granulations. The central large nodule developed around 
the needle entrance. Photographed on July 31, 1916. X12. 
3. —Middle of a Ricinus intemode, showing copious tumor-like proliferations due to 
the injection of a 20 per cent solution of urea. These proliferations were yellowish 
rather than a pure white, as in most cases. Injected June 29, 1916. Photographed on 
July 11. Xn. 
4. —Two Ricinus intemodes injected with a 10 per cent solution of tannic acid on 
August 7, 1916. Photographed on October 20. Natural size. Pith killed and black 
in the lower third of each; in the upper two-thirds a continuous sheet of proliferations 
from the pith surface with occasional nodules. The lower large nodules are wound 
reactions from deeper tissues. Each ceiling also shows proliferations. The killed 
part of the lower intemode was examined for crystals of calcium oxalate but only an 
occasional crystal was found, not more than would occur in normal stems of this age 
(see PI. 46). 
