•s 



bH PRINCIPLES OF GARDENING. [CH. II. 



rubbish. Roots coming in contact with these do not 

 tuni aside, but immediately cease extending in 

 length, and produce laterals. 



It may be accepted as an universal maxim, that 



whatever causes an excessive developement of root 



prevents the production of seed ; and vice versa, the 



production of seed, especially in tuberous-rooted 



plants, reduces the amount of root developed. Thus, 



, frequent transplanting the young plants of the* 



lettuce, brocoli, and cauliflower causes the production 



of nmnerous fibrous roots, and is found effective in jire- 



■ venting the mature plants advancing early to seed. 



: The early varieties of the potato do not naturally 



produce seed; but if their tubers are removed as 



soon as they are formed, these early varieties blossom 



and bear seed as freely as the later kinds, a fact 



suggesting many experiments to the cultivators of 



sin'-blooming tuberous-rooted flowers. Again, if 



. the blossoms of these later varieties are plucked ofl" 



\as they appear, the weight of tubers produced will be 



very materially increased. 



According to the usual acceptation of the term, 

 the roots of plants do not emit excrements, yet it is 

 quite certain that in common with all the other parts 

 of a plant they perspire matters differing in their 

 amount and composition in every species. The 

 earth in contact with the tubers of a potato fully 

 ripe contains mucilage, and has the peculiar odour of 



