EFFECTS OF THE GRAFTING AND BUDDING OF TREES. 345 



in the spring revive it, and give it strength to shoot forth, 

 and run in its few simple vessels up to the top of the dead 

 •wood. Warmer weather throws up the sap to the lop of 

 the old wood vessels, by the pressure of air below; but 

 the vacuum existing between the rind and bark prevents the 

 juice filling the last row or two of the wood, and gives it 

 the appearance of a fresh rind, which I at first took it 

 for; but on placing it in the solar microscope, I found it 

 was the last row of the wood. If you take off the rind at 

 this time, it will be found standing hollow, with an ap- 

 parent rind skin on the wood. A fter a time the blood of 

 the plant begins to form ; though in what manner I have 

 not the most distant idea, for it does not appear to me to 

 have any connection with the root. I do not however say 

 it has not : but I am now deeply studying this part, which 

 is that I know the least of. I hope however to make it 

 my winter study, as I have been collecting specimens for 

 more than two years for the purpose, and have now a large 

 collection of drawings from which I have not yet been able 

 to take the results, for want of time, and the interference 

 of grafting and budding. As soon as the blood is formed, 

 the bark and inner bark begin to grow, and I was sur- 

 prised to see, that they grew exactly in the same manner as 

 the bourrelets in the graft (see PI. IX, fig. 6 and 10.) At 

 first I could not reconcile this form to the usual form of the 

 growth of the bark, which is much the same in most plants; 

 but it is its inflated appearance, that disguises its natural 

 shape, and hides part of the lines as is seen at d d. It ap- 

 pears very evidently to prove, that there is no return of the 

 blood of the plant : it will not then be called a circulation. 

 I cannot therefore agree with the gentlemen,, who did me 

 the honour to notice my letters in the Panorama I think, 

 but I have not seen it, a friend having copied this remark to 

 send me.) " That the holes in the cylinders of the blood 

 vessels were intended to prevent the return of the blood, 

 or vegetable juice." Now there being so little motion in a 

 plant is the very reason, I should suppose, why it will be 

 the less likely to run contrary to the manner in which it 

 was intended ; and I do not believe, that there is any 

 circulation in this part. 



But 



