PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 185 



v 



The extremely unfavourable character of the season of 18(34 

 for the bean plant is best indicated by the late period at which 

 it attained maturity ; for, though the climate of Ayrshire is wet, 

 and harvest often late, it is only in quite exceptional seasons 

 that beans remain in the held till the beginning of November, 

 and when this happens, the crop is always small and inferior in 

 quality. It was most unmistakeably so on the present occa- 

 sion, for the produce was far below the average, and the beans 

 were a most inferior sample. The produce, as contained in the 

 foregoing tables, amounted to 3578'57 lbs. per acre, but it must 

 be borne in mind that this is the weight of the beans at the time 

 the crop was reaped, and when they still contained 60-3 per 

 cent, of moisture. After being stacked for some mouths the 

 quantity of water would have been greatly reduced, and their 

 weight would have diminished to less than half, or possibly to 

 about 1600 lbs. per acre ; and assuming 50 lbs. as the bushel 

 weight— which it certainly would not have exceeded— this 

 would give 32 bushels, or about 4 quarters per acre. 



The progress towards maturity is attended by a very great 

 diminution in the quantity of water in all parts of the plant, 

 but more especially in the stalks which now contained a very 

 much larger quantity of woody fibre than at any previous stage. 

 The leaves, too, had almost entirely disappeared, having become 

 black and rotten, and most of them having decayed and fallen 

 off. For this reason the amount of matters removed from the 

 soil appears to have diminished, and in point of fact the decay- 

 ing leaves had already returned to the soil from which they had 

 been derived. The composition of the ash of the different parts 

 of the plant has perceptibly changed. The leaves have gathered 

 into themselves a larger proportion of potash and phosphoric 

 acid, and there has consequently been a marked diminu- 

 tion in the quantity of those substances in the stalks. It is re- 

 markable, however, that the beans are by no means so rich in 

 potash as they generally are, for in place of 50 per cent., the 

 quantity they usually contain, there is here only 2631, or little 

 more than half that amount. 



Reviewing the whole results of these experiments, we find in 

 them further evidence, in addition to that offered by the pre- 

 vious series of researches on the turnip and wheat, of the ex- 

 tremely limited period of time within which the important cul- 

 tivated crops gather the great part of the matters which form 

 their mass. In the early part of their growth their progress is 

 extremely slow, but so soon as they have produced the organs 

 by which their food can be drawn from the soil and the air, they 

 start into active growth, and rapidly attain their full weight and 

 development, but after a certain period they make but little fur- 

 ther advance in point of size and weight, although great 



