388 



PR O DUCTI O N 



Sect. XV. i, 4 



r 



h 



buds from the lower parts of the caudex of the central ones, 

 are not generated in the bofonas of leaves, are of a more im- 



d 



d in that refpecl do not refen:ible the central bud 



bulb 



but require fome years before they fl 



Mr. Knig^ht has obferved, that the grafts from thofe fru 



h have been in public eftimation foi 



are now 



fo liable to canker, that they bear very little fruit,' and are not worth 



cultivation ; w 



he afcribes to th 



of the tree ; as a graft h 



And 



demands 



fays is fimply an elongation of the parent tree, 

 fome years to acquire the puberty neceliary for fexual generation, fo 

 it may become weak and inirritable by age, and perifli about the fame 

 time with the original tree ; which is fomewhat countenanced by 

 another remark of Mr. Knight, that the fummits, or long extremi- 



ties of old 



frequently die many y 



before fome fmall 



branches from the trunk, which continue to flourifh, as is frequently 

 feen in old oaks as well as in fruit-trees ; and which he might fup- 

 pofe to be occaiioned by the greater age of the terminal buds than 

 of the lateral ones, as well as from the greater length of their ab- 

 lorbent vefTels, and the confequent greater refiftance to the afcent of 



fap-j 



which may alfo be fooner impeded, or totally flopped 



by the inirritability of old age. 



Neverthelefs as the buds of trees are fucceffive progenies, and can- 



r 



not therefore be liable to old age, as they die anrlually ; the degeneracy 



of thofe which have lone fucceeded 



f the buds of very old trees, or 



ach other by their lateral, and not by fex 



^-' 



ft 



ai 



fe 



from their being liable to hereditary difeafes only, and not to hered 



mprovemen 



bferved above in Se6l. XIV 



Th 



degeneracy of fome pi 



6 



hereditary dif- 



eales, and not to old age, appears from their continuing for lono- 



uncouated periods of 1 

 berberries without feed 



me 



a 



ifter the produdlion of thefe difeafc 

 d vines without feeds, and ftrawbi 



without fruit, though probably with feeds, as the barren hautbois 



ftra wherries. 



I 



