46 OF REVERSED PLANTS. 



to elucidate this subject. Their stems, though of only 

 annual duration, are formed nearly on the same prin- 

 ciple as that of a Palm, and are really congeries of 

 leaves rising' one above another, and united by their 

 bases into an apparent stem. In these the spiral coats 

 of the sap-vessels are very easily discernible. 



To conclude this subject of the propulsion of the 

 sap, it is necessary to say a few words on the power 

 which the vessels of plants are reported to possess of 

 conveying their appropriate fluids equally well in either 

 direction ; or, in other words, that it is indifferent 

 whether a cutting of any kind be planted with its up- 

 per or lower end in the ground. On this subject also 

 Mr. Knight has afforded us new information, by ob- 

 serving that, in cuttings so treated, the returning ves- 

 sels retain so much of their original nature as to deposit 

 new wood above the leaf-buds ; that is, in the part of 

 the cutting which, if planted in its natural position, 

 would have been below them. It appears, however, 

 that the sap-vessels must absorb and transmit their sap 

 in a direction contrary to what is natural ; and it is 

 highly probable, that after some revolving seasons new 

 returning vessels would be formed in that part of the 

 stem which is now below the buds. I presume there 

 can be no doubt that successive new branches would 

 deposit their wood in the usual position. It is never- 

 theless by no means common for such inverted cuttings 

 to succeed at all. An experiment to a similar purpose 

 is recorded by Dr. Hales, Vegetable Sfaticks, p. 132, 



