96 POPULAB EHROES. 



being also to the vegetable what the brain and 

 spinal marrow are to animals — the source and seat 

 of life. Mr. Lindsay regarded it as being the 

 seat of the irritability of the leaves of Minosa. 



None of these theories are found in the writings 

 of botanists of to-day, though among the unedu- 

 cated, one still occasionally meets the belief that 

 the "heart " is the vital part of the tree. The real 

 office of the pith is mainly to serve as a place of 

 storage for supplies of starch and other food mate- 

 rials during winter. After a stem has .become old, 

 even this service is no longer rendered, and the 

 pith becomes more or less disorganized and is of no 

 apparent use. 



