TRANSPIRATION AND TEMPERATURES 45 



is to be seen that a general similarity to that of desert forms is exhib- 

 ited. The outer integument of the plant is developed in such manner 

 and furnished with devices for the prevention of damage from the ef- 

 fects of the intense insolation, and for preventing rapid radiation. 

 Either cause would result in an excessive transpiration and damage to 

 the chlorophyl apparatus and protoplasmic mechanism. No important 

 anatomical features of plants at high altitudes or high latitudes have 

 yet been discovered which might unquestionably be interpreted as 

 adaptations to an alpine or polar climate. 



