34 



TH« RELATION OP TRANSPIRATION TO PLAKT F00I5 

 TRANSFERRED TO THE PLANT. 



There seens to be two means of transferring plant food 

 to th« plant, viz., diffueion, and th© mechanical transfer 

 in the stream of water. The older plant phyeioiogiste 

 seem to lay e gr-^ater stress relatively on the form^rthan 

 do later investigator©. Storer, conforming to the views 

 of the older iscvestigators, cites the T^ardiaji ©aee, and 

 plants growing In the greenhouse where the air is moist, 

 as showing the importance of diffusion. Re assumes that 

 transpiration is not sufficient to cause the required trans- 

 fer of plant food. May not the passage of water through 

 the plant due to root pressure be greater than is assuHied ? 

 And may not the plant food in the artificial soils usually 

 employed under such e^ircxuastanees be more abundant, thus, 

 perhaps, re<iuiring less water to produce a givin amount of 

 dry matter ? Referring to the laeehanieal transfer of plant 

 food, Losw (Bu. Plant Industry 45, 11), states that, the 

 surplus of mineral matter found in plants, nutrient as well 

 as Indifferent compounds,- depends to a great extent uion 

 the intensity of the current of transpiration, which explains 



