446 Experiments upon the Potatoe, 



application of a knowledge of the laws that govern organic beings 

 has never yet been made to any object of great public interest. 



" The stems of Potatoes as of other plants," Mr. Knight observes 

 " rise perpendicularly under the influence of their unerring guide, 

 gravitation, so long as they continue to be concealed beneath the 

 soil ; but as soon as they rise above it, they are, to a considerable 

 extent, under the control of another agent, light. Each inclines 

 in whatever direction it receives the greatest quantity of that fluid, 

 and consequently each avoids, and appears to shun, the shade of 

 every contiguous plant. The old tubers being large, and, under 

 the mode of culture recommended, rather deeply buried in the 

 ground, the young plants in the early part of the summer never 

 suffer from want of moisture, and being abundantly nourished they 

 soon extend themselves in every direction till they meet those of 

 the contiguous rows, which they do not overshadow on account of 

 the w idth of the intervals. 



The stems being abundantly fed, owing to the size of the old 

 tubers, rise from the ground with great strength and luxuriance, 

 support well their foliage, and a larger breadth of this is thus, I 

 think, exposed to the light during the whole season, than under 

 any other mode of culture which I have seen ; and as the plants 

 acquire a very large size early in the summer, the tubers, of even 

 very late varieties, arrive at a state of perfect maturity early in the 

 autumn." 



Keeping these facts in view, Mr. Knight recommended the 

 adoption of the following rules. 



1 . Do not plant later than the beginning of March ; in order 

 that the Potatoes may have as long a period of growth as possible. 



2. Employ whole tubers, none weighing less than four ounces. 



3. Adjust the distances at which the tubers are planted in the 

 rows, and of the rows themselves according to the usual height of 



