134 PLANT LIFE ON THE FARM. 



its structure, the more dependent one upon another are the 

 structural elements of which it is compounded. 



Natural death may he described as an exhaustion of the 

 protoplasm its water evaporates or is drafted elsewhere ; 

 end so with its soluble or liquid contents the insoluble and 

 the useless remain behind. We see this in the case of the 

 leaves every autumn ; their protoplasm dries up, their 

 chlorophyll degenerates and disappears ; they are emptied 

 of starch and other matters, which are conveyed to some 

 other part of the tree to be stored up for future use by the 

 new growths in the following season, till at length nothing 

 is left but a framework of dry cellulose, a quantity of 

 mineral or earthy matter, and such material as could not 

 be dissolved or transported. In other organs the con- 

 tinuous maturing process at length results in the blocking 

 up of the cells aud tubes by continued deposit in the 

 interior. Osmosis can no longer go on between them, 

 for their altered structure prevents it, and in conse- 

 quence the protoplasm disappears. Just as in human 

 beings, the minute blood-vessels get " bony " or otherwise 

 deteriorated in structure, so do the cells and fibres of 

 plants become unfit to carry on the processes of life. 



For the purposes of the cultivator, it is very desirable 

 that he give an eye to the way in which plants die and to 

 the causes in which induce death. The subject may be 

 looked at from various points of view. From the structural 

 point of view, death may begin in the cells of the root, 

 in those of the stem, in those of the intermediate " collar," 

 or in those of the leaves, and the appearances presented 

 will be found to differ correspondingly. 



From a physiological point of view death may result from 

 starvation or from suffocation ; the process in each case may 



