124 Agricultural Experiment Station, Ithaca, N. Y. 



case, tlie outer tissues being quite firm, the radial elongation frequently 

 takes place in the deeper lying thin walled cells. In the preparation 

 of the plants for forcing the lateral shoots are cut off. In the spring, 

 when placed under conditions of forced culture in the plant houses 

 there being few buds where growth can take place and thus relieve the 

 stem of the great amount of water absorbed by the roots, localised 

 centers display abnormal tiirgescence through the radial stretching of 

 the cell walls. 



In 18 'J 9 experiments were conducted under the direction of 

 Sorauer, in \he forcing houses at Pankow, near Berlin, with Avell 

 rooted stems placed under conditions favoring forced growth. The 

 results were quite positive, excellent examples of the trouble being thus 

 produced. 



He cites similar developments in the stems of young plum plants in' 

 water culture where the base of the stem was set too deep in the water. 

 Also plants of Phaseolus vulgaris were subject to the trouble, when 

 cultivated in wet sand if the seedling was too deep in the soil. 



Masters,* at a meeting of the Royal Horticultural Society in 1878, 

 showed leaves of potatoes, the under surface of which was marked 

 with warts similar to those which occur on vine leaves when grown in 

 too close ^and moist an atmosphere. The conditions under which the 

 potatoes were grown were such as to produce the growths in question. 



In 1889, vine leaves were exhibited at a meeting of the same society, 

 which possessed similar warts on the under surface. The vines were 

 grown under glass. Ward, to whom the matter was submitted, said it 

 was due to poor ventilation of the house whereby the humid atmosphere 

 favored abnormal turgescence which resulted in these outgrowths.f 



Quabius X reports the trouble on pears grown out doors, which is the 

 same as that in Hibes aureum. 



Conclusion. Root pressure varies greatly in different plants. It 

 would be interesting to know if there was any variation existing in the 

 root pressure of different varieties of tomato plants grown under the 

 same conditions, and if there was any correlation between the unit of 

 pressure and the susceptibility of the variety to the oedema; or, if 

 root pressure is constant in the different varieties, does any variation 

 exist in the power of the stem to lift the water which the roots absorb ? 



The study thus far made and presented in this report is in the nature 

 of a contribution toward a solution of the at present obscure and 



* Gardener's Chronicle, 1878, I, p. 802. 

 t Gardener's Chronicle, 1889, I, p. 503. 



:!: Wasseraucht bei Birnen. Jahresb. d. Schles. Centralvereiu's fiir Gartner 

 und Gartenfreunde zu Breslau, 1881. See Just's Bot. Jahresb, 1872, ii, p. 704. 



