ON PEAKS. 



Ill 



Pis. I. 



portion of it. The limb is constricted, and is nearly ono (|uarter smaller tUan tlie adjacent 

 parts above or l)i'!inv. This constricied portion appears so perfectly dead and dry, that it 

 seems impossible for the sap to pass through it and reach the vigorous and living portion 

 beyond; which is not only bearing large leaves but also fruit, which is also equally as 

 large and promising as that upon any of (he unaffected limbs. 



The eflfect of the disease as exhibited in very numerous instances, is much the same as 

 that which follows from ringing a branch ; a process by which (he circulation, as is main- 

 tained, is interrupted. lis descent to (lie root is at lensl partially prevented, by which 

 there is an accuinulation at all times of nnlri(ious Ihiids in the limb above (lie removed or 

 injured bark and wood. The constriction where the disease is sealed is mechanically 

 arrested, however, with the ascent and descent of the sap; for here it is evident, by the 

 dry state of lliis portion of the limb, that its vessels are nearly impervious; and after a 

 short lime they become entirely so — the dis- 

 ease passing from outside to inside, and not in 

 the opposite direction. The circulation, there- 

 fore, is sustained by the interior. It would 

 seem from an inspection of the dying branches 

 that it is almost impossible, in many instances, 

 for the sap to pass along the limb ; still, there 

 is no doubt that this it does so long as a green 

 leaf appears. 



The following cuts exhibit the facts we have 

 stated ; and it may, if followed out, throw new 

 light upon J.he circulation of sap, and of the 

 nutrition of vegetables. 



Fig. 1. Part of a blighted branch of an 

 apj)le (ree, wiiich was taken from the garden 

 of E. P. Pkentice, Esq., of Albany. 



a, Dead bark and wood ; b, living bark and 

 newly formed wood ; c, constricted portion of 

 the stem, and dead upon the outside; e, inte- 

 rior of the stem, showing signs of life ; f, liv- 

 ing and luxuriant growth of part of the branch. 



In this example there is quite a thickened 

 stale of the branch at a, which in the speci- 

 men, is strongly contrasted with the part be- 

 yond the dead portion ; as it is about \ thicker 

 by the formation of new wood since it was 

 attacked by the blight. Most of the new 

 growth has taken place since the time when 

 a branch usually acquires the length of stem 

 for (he season. In (ho bark, or immediately 



