PLATE 17 
1, 2.—Cross sections of two intemodesof Ricinus communis (two plants), showing 
pith proliferations due to the feeble alkaline vapors from monobasic ammonium 
phosphate. An open glass tube containing 0.2 c. c. of a 5 per cent water solution 
of the phosphate was inserted into the lower end of these intemodes and sealed in on 
August 7, 1916. The plate shows sections of the upper end of each intemode. The 
lower was more responsive than the upper, probably because younger, although 
the upper shows granulations from all parts of the pith surface. Photographed on 
August 17. X8. 
