70 AGE, GROWTH, AND DEATH 



nerve. The first figure shows these cells as they 

 exist in their first maturity ; the second figure, 

 as they appear in a person of extreme old age. 

 In the latter you will readily notice that the cells, C, 

 have shrunk and no longer fill the spaces allotted to 

 them, the nuclei have become small, and have lost 

 their conspicuous granules, and the protoplasm has 

 changed its appearance very strikingly because there 

 have been deposited in it granules of the pigment 

 which impart to these cells an appearance very differ- 

 ent from that which they had in their maturity when 

 their functional powers were at their maximum. You 

 will notice also in other parts of the second figure 

 that the atrophy of the cells has led on to their disin- 

 tegration (c, c), that they are breaking down, being 

 destroyed, and that the result of their breaking down 

 will ultimately be their disappearance. Thus the 

 atrophy of a cell may lead to its death. The other 

 two figures 1 upon the screen show us the brain of 

 the humblebee. On the left is the brain of the bee 

 in the condition in which we find it when the bee 

 first emerges from the pupa or chrysalis. The cells 

 are then in a fine physiological condition, but in a 

 few weeks at most the bee becomes old and in the 

 space which belongs to each cell we find only its 

 shrunken and atrophied remnants, the nucleus greatly 

 reduced in volume, and an irregular mass of protoplasm 

 shrunk together around it. These cells have likewise 

 undergone an atrophy and are on their way to death. 



1 The two figures of the bee's brain are not reproduced in the text. 



