CHAPTER XXX 



PATHOLOGIC PLANT ANATOMY (CONTINUED) 



HYPERTROPHY 



The plant pathologist applies the word hypertrophy to an abnormal 

 process of growth in which the individual cells are larger than the nor- 

 mal, or when whole tissues become enlarged, or distended. Cell 

 division is left out of account as a means of the formation of hyper- 

 trophied cells, or tissues. The cells which are enlarged may be derived 

 from the meristematic elements, which have continued their growth to 

 the enlarged size, or cells continue their growth longer and more in- 

 tensively, or cells of permanent tissue are concerned, which take up 

 anew the process of growth in size. The cell may enlarge in all of its 

 dimensions, so that the original shape of the cell is maintained, or it may 

 enlarge in one or two directions, when the original shape is no longer 

 kept. If the enlargement is in two directions the cell will be distorted, if 

 in one direction it wiU grow abnormally long. The extent of the en- 

 largement and its direction will be determined by the character of the 

 surrounding cells, or their absence. An hypertrophied cell may be 

 surrounded by cells incapable of distention, hence its enlargement will 

 be limited to the size of the available free space. Kuster distinguished 

 two kinds of hypertrophy, cataplastic and prosoplastic. Cataplastic 

 h)^ertrophy is an abnormal increase in the volume of cells associated 

 with degenerative atrophy of their living contents, for the functional 

 decline of the cell has been termed by Beneke, cataplasia. Prosoplastic 

 hypertrophy involves new anatomic characteristics and functional 

 activities, for the cells store up fats, proteins and starches, or develop 

 chlorophyll, or red coloring matter. The involution forms of Bacillus 

 radicicola, which forms the leguminous root tubercles, and those of 

 the crown-gall organism, Pseudomonas tumefaciens, are examples of 

 simple hypertrophied cells (Fig. 143). With these preliminary remarks 

 it is important to illustrate the different kinds of hypertrophy which 

 have been described by plant pathologists. The most simple cases are 

 those in which the meristematic cells capable of division have grown to 



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