368 



Besides sugar and fodder beets, potatoes sufifer most frequently : also 

 roots of the Umbelliferae, such as celery, carrots, parsley, etc.; more rarely 

 the fleshy roots of cabbage plants. This condition is characterized by the 

 destruction of the cork layers. For some time they are replaced again and 

 again by the underlying tissues. Fig. 52 illustrates a sugar beet suffering from 

 "zonal deep scurvy" or "girdle scun-y," the worst form of this disease. 

 The beet is 7 to 8 cm. thick at its head, but is circular only at the top ; while 

 en both sides where the roots grow, there is a considerable flattening which 

 disappears again toward the lower end. The flattened sides are depressed 

 like troughs and the centre of the trough is possibly 6 cm. away from the 

 cut surface at the head of the beet. The inner surface of the trough is 

 wavy because, around the very deep centre, the different layers of the beet 

 flesh rise like terraces aboxe one another towards the outer edge in more or 

 less clearly defined zones. 



The consistency of the tissue at the edges of the trough is tindery, 

 scurvy-like, i. c. fissured and the fissures traversed by tube-like passages, 

 which initiate a fibrous decomposition of the substance. The passage-like 

 fissures are lined with brown, corked, jagged pieces of tissue, whose sur- 

 faces show a peculiarly grainy decomposition. In spite of the deep decom- 

 position at the place attacked, we find that the beet retains the ability to 

 react, for the edges of the various rings of vascular bundles, because of a 

 new cell ff)rmati()n. curve out like ramparts after the injury. 



That the growth of the beet at the scurvy places may previously have 

 been somewhat arrested is evident from the fact that, on the injured side of 

 the beet as well as on the opposite side, the different tissue rings are smaller 

 than on the other sides. If cross-sections of the diseased plants are treated 

 with sulfuric acid, it is found that beneath the brown, dry, gradually de- 

 composing tissue layers, which have turned to cork, the intercellular sub- 

 stance of the apparently healthy root flesh assumes a yellowish, wine-red to 

 bright carmine tone. Often some duct groups also seem to be provided with 

 solid balls, or stoppers, which assume the same color when treated with 

 sulfuric acid. Later the intercellular substance is found to be broken up 

 and finally begins to decompose into a grainy slime. To the naked eye the 

 whole process seems a form of dry decomposition. 



As already mentioned, this form of scurvy which extends so deep into 

 the flesh of the beet, is less frequent. We usually find much flatter, bark- 

 like fissures, occurring in circular areas, and often showing that they have 

 appeared in a rather early developmental stage of the beet, but later have 

 stopped spreading. It is worth noting that, in the zonal deep scurvy, the 

 head of the beet does not seem to be attacked, but the disease becomes 

 visible first at a certain distance below this, in the soil. In too deeply 

 planted beets the first traces of scurvy are often found at the base of the 

 petioles. Ver\^ similar phenomena are noticed also in potatoes, carrots, etc. 

 In potatoes, it has been observed that the scurvy formation extends out 

 from the lenticels. If we examine such a lenticel, we perceive without difli- 



