28 PRESENT DISEASE IN THE POTATOE. 



CHAPTER IV. 



ON THE GANGRENE OF THE POTATOE, OR PRESENT DISEASE 

 IN THE PLANT. 



Disease of potatoe (102). Mortification (103). Commencement of 

 and propagation in leaves, stalks (104 107) ; in under-ground 

 stem (108); in collar (109). Modes of proceeding (110113); 

 in tubers (114) ; in seeds (120). Odor in (121). Dryness of leaf 

 in (122). Diseased plants (123). Plants not injured (124); 

 afterwards die (125). Primary effect (126). Entire plant dis- 

 eased (128). Top of haulm left (129 132). Continuity of dis- 

 ease in future plants (132). Period of growth when affected by 

 disease (134136). Diseased potatoes bad (136). Structure 

 impaired (137). Decomposed (138 141). Irregular cavity (142, 

 143). Shrivelling of (143.) General character of alteration 

 (144). 



(10*2.) THE potatoe plant has lately become the subject 

 of a peculiar disease, by the operation of which a larger 

 or smaller part of the plant loses its proper characters and 

 dies. 



(103.) This disease is mortification, or gangrene, in the 

 truest sense of the term, and presents itself for our consider- 

 ation under two varieties, as gangrena sicca, or dry gan- 

 grene, where the part shrivels up and becomes quite hard 

 and desiccated, and gangrena liumida, or moist gangrene, 

 by which the potatoe becomes disorganized by rotting, and 

 is wet and offensive. 



(104.) Upon examination we find that this gangrene 

 may commence in various parts of the plant, and produces 

 consequences important to the vitality of the plant, com- 

 mencing at the spot which it first attacks. It may attack 



