EDGAR TULLIS 



451 



isolated this phenomenon of disease, because it has an essentially practical 

 significance in the cultivation of Fiscus as a market plant. 



The disease occurs less often in plants grown for sale than in home 

 ornamental plants, where it may lead to a premature defoliation. My experi- 

 ments prove that it is produced by giving excessive heat and water to plants 

 when their growth has stopped and their transpiration lessened, thus stimu- 

 lating them to renewed activity. I produced intumescences by keeping a 

 rubber plant in a very hot room and giving it abundant water after it had 

 made a vigorous summer growth and passed into the normal resting period, 

 instead of the cooler, drier environment which it should naturally have had. 

 Leaves fell immediately, while intumescences were formed on the younger 

 ones. \Mien the plant was put in a light, but cooler place, the leaves with 

 the intumescences remained on the stem until the next summer, when the 

 plant again grew nor- 

 mally if somewhat more 

 weakly. 



This kind of disease 

 and its cure may be 

 considered characteris- 

 tic. The intumescences, 

 therefore, are highly sig- 

 nificant symptoms of ab- 

 normal turgidity in all 

 plants. As soon as they 

 show themselves, the 

 plant must be put into a 

 light, cooler environ- 

 ment and given a de- 

 creased water supply. 



The Skin Diseases of *''§"• SS. Hyacinth bulb infected with the pustules of 

 ^_ the skin disease- (Orig.) 



Hyacinths 



■v scales which have lost their gloss, d formation of pustles, 

 _, , . , /dried edge, k voung- bulb. 



i h 1 s phenomenon 

 (Fig. 88) has not been considered, although it occurs very frequently. 

 Normally the outer scale leaves are smooth, firmly enclose the bulb, and 

 usually extend up to its neck. In this disease they are short and die back 

 from the dying edges. Often such hyacinth bulbs crack open and are 

 thickly covered with dry leaves, especially near the place torn. On the still 

 fleshy outer parts of the bulb, colonies of the blue-green mold {Penicillium 

 glauciim) frequently occur. 



The leaves standing isolated, or connected with one another, are flat- 

 tened on the upper side and often many boil-like, swollen, yellow places 

 appear. In the colored part also of normally dried bulb scales, they almost 

 always show some mycelium. In cultures this is proved to belong to 

 Penicillium. The tissue of such diseased places differs from that of normal 



