6 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



distance varying from that of a fraction of the radius of a cell to 

 many meters to the protoplasts which are to make use of it. The 

 origination or the hydrolyzation of this material is a chemical 

 process, and the rate or velocity at which it takes place is one 

 which may be assumed to bear the relation to temperature by 

 which it doubles or accelerates even faster for every rise of lO 

 degrees C. 



Diffusion is much less affected by temperature, hence the rate 

 and amount of translocation is much less affected by temperature. 

 When the dissohed food reaches the mernbrane or the periphery 

 of a protoplast it is then in a position of being about to become 

 part of the integral substance of bodies of widely different compo- 

 sition, and it must therefore be taken for granted that for the 

 growth of different organs, tissues, or protoplastic members, the 

 food-material must be converted into "building material." 



This building material must be of a highly specific character, 

 and that such special stuffs are formed in the growth and develop- 

 ment of the complex plant is the conclusion to which all morpho- 

 genic experiments converge during the last decade. Non-develop- 

 ment under conditions inhibiting the construction of "formative 

 stuffs" is now well exemplified by a score of investigations, the 

 latest available results being those of my own in which the form 

 of the polymorphous leaf of Neoheckia might be attributed to 

 special materials.^ The induction or inhibition of llowcr forma- 

 tion, fruit-development, tuberization, spore-formation, conjuga- 

 tion, etc., in plants from the algae to the Compositae by variation 

 of external conditions is a matter of the commonest observation 

 and in every analyzed instance has yielded the single conclusion 

 that such action is through the formation or lack of formation of 

 special building materials. 



The initiatory stage of the supplying of food to a growing part 

 of a plant may or may not be a chemical change, the second link 

 is one of diffusion or osmosis, and the third must inevitably be 

 one of chemical change as a consequence of which temperature 

 plays the dominating role, affecting not only the rate at which 

 such changes take place, Init also to a lesser extent the perme- 

 ability of membranes and the'lndratation capacity of the colloids 



» MacUoiigal, D. T. The dctcrminativt; action of (.nvironic factors upon Neoheckia 

 aqtialica Grvcni;. Flora 1 06: 265-280. 1914. 



