472 BOTANICAL WORK OF THE BRITISH ASSOCIATION. 



always use language with which we could agree, nothing could ruffle 

 either his imperturbable good nature or the noble simplicity of his 

 character. Truth to tell, we were often in friendly warfare with him. 

 But I rejoice to think that before his peaceful end came he had patiently 

 reconsidered and abandoned all that we regarded as his heresies, but 

 which were in truth only the old manner of looking at things. And 

 I think that if anything could have contributed to make his departure 

 happy, it was the conviction that the completion of his work and his 

 scientific reputation would remain perfectly secure in the hands of Dr. 

 Scott. 



VEGETABLE PHYSIOLOGY. 



Turning again to the present, the difficulty is to limit the choice of 

 topics on which I would willingly dwell. In an address which I deliv- 

 ered at the Bath meeting in 1888, I ventured to point out the impor- 

 tant part which the action of enzymes would be found to play in plant 

 metabolism. My expectations have been more than realized by the 

 admirable work of Professor Green on the one hand, and of Mr. Horace 

 Brown on the other. The wildest imagination could not have foreseen 

 the developments which in the hands of animal physiologists would 

 spring from the study of the fermentative changes produced by yeast 

 and bacteria. These, it seems to me, bid fair to revolutionize our whole 

 conceptions of disease. The reciprocal action of ferments, developed 

 in so admirable a maimer by Marshall Ward in the case of the ginger- 

 beer plant, is destined, I am convinced, to an expansion scarcely less 

 important. 



But, perhaps, the most noteworthy feature in recent work is the dis- 

 position to reopen in every direction fundamental questions. And 

 here, I think, we may take a useful lesson from the practice of the 

 older sections, and adopt the plan of intrusting the investigation of 

 special problems to small committees, or to individuals who are willing 

 to undertake the labor of reporting upon special questions which they 

 have made peculiarly their own. These reports would be printed in 

 extenso, and are capable of rendering invaluable service by making 

 accessible acquired knowledge which could not be got at in any other 

 way. 



We owe to Mr. Blackman a masterly demonstration of the fact, long 

 believed, but never, perhaps, properly proved, that the surface of 

 plants is ordinarily impermeable to gases. Mr. Dixon has brought for- 

 ward some new views about water movement in plants, which I confess 

 I found less instructive than many of my brother botanists. They are 

 expressed in language of extreme technicality; but as far as I under- 

 stand them, they amount to this: The water moving in the plant is 

 contained in capillary channels; as it evaporates at the surface of the 

 leaves a tensile strain is set up, as long as the columns are not broken, 

 to restore the original level. I can understand that in this way the 

 "transpiration current " may be maintained. But what I want to know 



