14-0 



LIVING PLAXTvS 



mount to a maximum, the supply may be 

 found insufficient, unless supplanted by the 

 food-forming activity of the lamina, and de- 

 terioration of the tissues, due to starvation, 

 must ensue. 

 The stage in which the translocated food 

 Growth with becomes inadequate is not identical in all 

 insufficient specics. Thus it appears from my experi- 

 nutrition ments that relatively small leaves, or those 



with less rapid development, or with a read- 

 ily available supply of food material, may 

 attain a much more advanced stage than 

 those in which the contrary conditions pre- 

 vail. The conditions may be so favorably 

 disposed as to allow not only of the complete 

 development of the leaf, but also of its contin- 

 ued maintenance under conditions of func- 

 tional inactivity with respect to the chloro- 

 phyll. 



It is to be noted that the phrase, * 'function- 

 al inactivity," is used in a relative, not an 

 absolute sense. The portion of the plant en- 

 closed in the apparatus is constantly emitting 

 carbon dioxiile ; which is rapidly absorbed by 

 the potassium solutions. Under such circum- 

 stances the carbon dioxide may be imagined 

 as forming a diffuse stream from the plant to 

 the potassium, and the amotmt actually 

 available by the chlorophyll-bearing cells at 

 anv one time must be extremely small. Some 



