SOLUTE DISTRIBUTION AND BEHAVIOR 241 



tion for the failure to obtain food. From the standpoint 

 of diffusion gradients or turgor gradients one would expect 

 solutes to move more readily to the fruit with a low food 

 content and not to the one that already has a higher food 

 content. Eventually the conducting tissues leading to the 

 successful fruit may become better developed than those 

 leading to the unsuccessful fruits, but this difference is 

 probably developed after growth differences have taken 

 place, not before, and is not in this sense causal. An 

 indefinite appeal to influences, stimuli, or hormones merely 

 seems to beg the question. 



A possible explanation which seems to me more definite 

 and possible of experimental test may be based on the 

 assumption that translocation is actually carried on by the 

 streaming protoplasm within the conducting cells. Start- 

 ing with two blossoms with equal potentialities if one, A, 

 is cross-pollinated with active pollen that induces the 

 development of vigorous seed, while the other, B, is 

 poUinated with ineffective pollen, then the more effective 

 pollen will probably induce higher activity in the gynaecium 

 of A. White (1907) found the respiration of gynaecia of 

 11 different species of plants to show a marked increase 

 4 to 5 days after pollination, while similar flowers not 

 pollinated showed no such change. In one instance where 

 abortive pollen was used there was no increased carbon 

 dioxide production over that of the flowers not pollinated. 

 One might expect this increased activity to increase the 

 streaming or interfacial activity of the protoplasm of these 

 tissues, which in turn would hasten the movement of 

 foods. It is very possible that this increased activity in 

 protoplasmic streaming is propagated back through the 

 conducting tissues. I know of no direct evidence to this 

 effect and this is a weak point in this explanation, but it 

 should be capable of verification or disproval.* If the 



* Heilbrunn (1928, p. 295) makes the following statement but cites no 

 evidence: "A third aspect of protoplasmic activity ... is the fact that 

 whenever protoplasm is made active, the effect tends to be transmitted 

 from one part of a cell to another, and from one cell to another." 



