CHARACTER OF THE TUMOR. 161 



ably begins in a single cell or in a few cells and perhaps from a special 

 tissue, but whether the impulse to division must always come from 

 within the infected cell, this impulse being transmitted only to its 

 daughter cells, and so on, or may also be external, influencing neigh- 

 boring groups of cells, remains to be determined. 



When this double phenomenon appears, to wit, overproduction of 

 parenchyma and corresponding reduction of vessels, and it occurs 

 very often not only in the daisy, but also in the sugar beet, peach, 

 hop, and many other plants, the tumors do not appear to be able to 

 obtain as much water and nourishment as is required to carry them 

 beyond a certain point in growth, and portions of the morbid tissues 

 slough off, necrosis following growth in the course of a few months. 

 It is seldom that the primary necrosis involves the entire tumor; 

 some portion of it, generally the margin, remains alive and proliferates 

 more or less extensivel}^ the same season or the following season, 

 forming additional tumor tissue, which subsequently extends the 

 open wound by additional necrosis. Where the woody fibers are 

 more abundant this phenomenon does not occur, or takes place at a 

 more remote date. In other cases the tumor regresses and no new 

 one appears. 



SUGGESTED RELATIONSHIP TO ANIMAL TUMORS. 



The writer can not help feeling that the phenomena displayed in a 

 rapidly proliferating tumor of the type figured and described in this 

 bulletin show^s a likeness to certain tumors occurring in the animal 

 body, namely, to sarcomata. These plant tumors often grow very 

 rapidly, and when the plant is a small one either destroy it within a 

 few months or greatW injure it. They seem to be much more nearly 

 related to sarcomas than they do to inflammatory i)rocesses, to which 

 some of the animal pathologists with whom we have talked have been 

 inclined to liken them. 



Exclusive of the presence of leucocytes, which do not occur in 

 plants, and of swelling, which even in animals is not the invariable 

 accompaniment of an abscess (e. g., abscess in bones), we have in 

 plants phenomena quite like abscesses in animals, but these phenom- 

 ena are in no way like crown-galls. They consist of the formation in 

 the stems or other parts of plants of more or less extensive cavities 

 or chains of cavities filled with fluid, broken down portions of the 

 tissues, and a greater or less number of the bacteria which have caused 

 the disorganization, together usually with saprophytes of various 

 kinds. Such phenomena occur in bacterial diseases of potato, maize, 

 sugar cane, cabbage, pear, etc., but they are purely disorganizations 

 (areas of softening), not ahnormal organization iwocesses. In the 

 abscesses no new organs are formed. The most the plant is able to 

 78026°— Bull. 213—11 11 



