(Edema of the Tomato. 123 







turgescence could no longer be relieved. In making a section of a 

 stem at this point before the radial elongation of the superficial layers 

 of cells began, it would be possible to tell on which side of the stem, 

 or at what points on the circumference, the cushion would be 

 developed. All of the cells in such succulent, rapidly developed stems 

 are proportionately large and thin walled. But the force of the 

 excessive turgescence has produced unequal results in the size of the 

 cells at various points in the cortical parenchyma and the adjacent col- 

 lenchyma and epidermis, so that the section shows much larger cells 

 with consequently thinner walls at ont> or more pointlfe outside the 

 cambium ring. 



Not only do these cells contain more water but their cell walls are 

 less resistant. It is at these points the radial elongation of the cells 

 takes place, as can be seen by a comparison of numerous sections of 

 affected stems. 



In farther confirmation of this fact, that active growth relieves the 

 tension and prevents the trouble temporarily, is the following observa- 

 tion made on the plants of the No. 18 variety which grew on the 

 south bench at a point where the glass was about four feet above the 

 soil. Before the growing ends of the plants reached the glass, the 

 terminal portion, of five or six inches, was entirely free and the plants 

 were in all respects similar to those of the same variety grown else- 

 where, though perhaps not quite so rank and succulent. When the 

 tops reached the glass their cramped condition, the greater humidity 

 and other contingent circumstances prevented growth or reduced it to a 

 minimum, Turgescence, however, continued, and in a few days nearly 

 the entire surface of the terminal portion of the plants showed the 

 development of these cushions. The trouble extended to the very end 

 at the base of the leaf bud, and the very young and intermediate leaves 

 were also affected, while plants of the same variety in other parts of 

 the house, where there was still freedom for growth of the shoots and 

 leaves, were no different from their former condition. 



Similar developments in other plants. Reference has been made to 

 probably a similar outgrowth produced on. potato stems by placing 

 rapidly growing potted potato plants under a bell jar.* 



Sorauerf also describes a similar disease on Mibes aureum,. In this 



* Ward, on some relations between host and parasite, etc. Proceed. Roy. Soc, Vol. 47 

 1890-1891, p. 393-443. 



t Wassersucht bei Ribes aureum, Frelhoffs' Deutsche Giirtnerzeitung, Aug., 1880. See Just's 

 Bot. Jahresb, 1880. 11 Abth. p. 656-657. 



Sorauer, Pflanzankrankheiten, Zweite Auflage, Bd. I, p. 235-238. 



Goschke, Die Wassersucht der Ribes, Monatsschrift d. Verein z. Beford d. Gartenbaues in 

 denkgl. Preuss. Staaten, Octoberheft, 1880, s 451. See Just's Bot. Jahresb, 1880, II Abth., 

 p. 657. 



