SOIL EXHAUSTION AND ROTATION OF CROPS. 147 



the varieties was nearly white, with those splashes of red; the 

 other a red potato. 



The Chairman. How do they differ in quality? 



Mr. Yeomans. The quality was decidedly given to this 

 mongrel by the red potato. It is poor. It is not fit to eat. 



Mr. Olcott. I have raised the Rhode Island Peachblow, 

 called the White Apple, and I have noticed that some seasons 

 it has been much redder than in other seasons, and the years 

 when the potatoes were red the quality was invariably poor. 

 The other instance of the apparent mixture of the old Black 

 Mercer with some other potato, I cannot account for, but the 

 red patches he observed, it seems to me, are easily explained. 

 I have observed the same thing with the Red Peachblow a 

 good many times, to my chagrin. I do not like them. 



Adjourned to Thursday, at 10 A. M. 



THIRD DAY. 



The meeting was called to order soon after ten o'clock on 

 Thursday morning by Vice-President Hyde, who stated that 

 Prof. Johnson would continue his lecture of yesterday. 



SOIL EXHAUSTION AND ROTATION OF CROPS. 



Prof. Johnson. I was speaking yesterday on the peculiar- 

 ities of plants wWch enable them to act differently on the 

 stores of nutriment which may be supplied to them in the 

 soil. I spoke of the difiFerences in the absolute quantity of 

 roots which various plants put out into the soil, and also of 

 the differences in the depths of roots ; and gave some illus- 

 trations on those points. I propose to speak this morning of 

 the different structure of the foliage of plants. 



We know with absolute certainty that a large share of the 



