AGE, GROWTH, AND DEATH 



We turn now to a representation of a section of 

 one of the orbital glands. This is very instructive 

 because we see not only that the cells which compose 

 the gland have acquired a special character of their 

 own, but also that they are not uniform in their ap- 

 pearances. This lack of' uniformity is due chiefly to 

 the fact that the cells change their appearance accord- 

 ing to their functional state. We can actually see in 

 these cells under the microscope the material im- 

 bedded in their protoplasmic bodies out of which the 



A B 



FIG. 15. To SHOW THE ORBITAL GLAND OF A DOG. A, with the material to 

 form the secretion accumulated within the cells. , after loss of the material 

 through prolonged secretion. From R. Heidenhain after Lavdowsky. 



secretion, which is to be poured forth by the cells, is 

 to be manufactured. So long as that material for 

 the secretion is contained in the cells, the cells appear 



