330 



THE GROWTH OF THE BRAIN. 



emerged in the perfect form. In this ganglion of the 

 bee the cells actually disappear with age, and Hodge 

 has estimated that for each cell present at senile death 

 there were in the insect just emerged 2*9 cells. 



These changes will probably be found more widely 

 distributed in the central system when search is made 



J. 



FlG. 77. To show the changes in nerve cells due to age. i, spinal 

 ganglion cells of a still-born male child ; 2, spinal ganglion 

 cells of a man dying at ninety-two years ; N t nuclei. In the 

 old man the cells are not large, the cytoplasm is pigmented, 

 the nucleus is small, and the nucleolus much shrunken or 

 absent. Both sections taken from the first cervical ganglion, 

 X 250 diameters ; 3, nerve cells from the antennary ganglion 

 of a honey-bee, just emerged in the perfect form ; 4, cells 

 from the same locality of an aged honey-bee. In 3 the large 

 nucleus (black) is surrounded by a thin layer of cytoplasm. 

 In 4, the nucleus is stellate, and the cell substance contains 

 large vacuoles with shreds of cytoplasm. (Hodge.) 



for them, for pathologists at the present time find the 



