68 



AGE, GROWTH, AND DEATH 



to carry the change yet further and to make it so 

 great that it goes beyond perfection of structure, so 

 far that the deterioration of the cell comes as a con- 

 sequence. Such cases of differentiation we speak of 

 as a degeneration, and it may occur in a very great 



FIG. 23. GROUP OF FIVE NERVE CELLS 

 FROM THE FIRST CERVICAL GANGLION OF A 

 CHILD AT BIRTH. Specimen preserved with 

 osmic acid. X 500 diams. After C. F. 

 Hodge. 



number of ways. Very frequently it comes about 

 that the alteration in the structure of the cell goes so 

 far in adapting it to a special function that it is un- 

 able to maintain itself in good physiological condition, 

 and failing to keep up its own nourishment it under- 

 goes a gradual shrinkage which we call atrophy. A 

 very good illustration of this, and a most important 



