2f^ 

 stagnant water. Here small qiiantities of is present and animals 

 o'btain most. From study of water plants it lias been shown that 

 large spaces for air always exist. "eed for therefore modifies 

 water-leaf. 



Bmlssion of CO and il. 

 Unlikely tliat these factors influence shapes and forms at all. 



Transpiration. 

 One of the greatest factors, cjreatest in size and one of the 

 greatest in form. Transpiration mainly determines difference 

 between sixe of leaves in shade and sun. Extremes. Impations. 

 Large thin entire leaf and Saticormia where leaves have been lost 

 entirely. 



Linden shows this, since leaves are larger near base, and 

 thinner, smaller and tliicker above. This can best be explained 

 by transpiration conditions. TTeed for protection from excessive 

 transpiration changes plants from hori^ontality to verticality as 

 seen in the desert types. Succulent plants explained best Ij;- this 

 factor. Rosette plants can also be explained as to those in cold 

 regions, but desert plants not so easy. 



