202 PROPAGATION. 



Repeated transplantation of herbs has a tendency 

 to increase their spreading- or stocky bulk rather than 

 their aspiring growth ; as exemplified in many species 

 of our culinary plants, as lettuce, broccoli, &c. The 

 reason seems to be their expansion, that is the elon- 

 gation of their stem, leaves, and roots, receiving fre- 

 quent checks, induces new births of roots, a shorter 

 stem, broader leaves, and, in the case of most sorts 

 of broccoli, larger flower-heads. 



A very frequent error is committed in trans- 

 plantation by placing the root too deep. This is 

 well known to be hurtful to the plant ; indeed so 

 much so, that there is no readier way of killing a 

 tree than by burying the roots. 



SECTION III. 



Propagation. Nature has provided for the per- 

 petuation of every species of plant found on the face 

 of the earth, chiefly by dissemination, and also by 

 viviparous progeny parted off from the parent station. 

 Among all plants exisfing in a state of nature these 

 processes go on constantly and uniformly without 

 human interference ; but when they are domesticated 

 and brought into cultivation for the peculiar uses, 

 directly or indirectly, of man, their original habits, 

 forms, and qualities become so changed, that much 

 variation ensues. Some of these variations are en- 

 largements of the stem or of the leaves ; others of 



