ON THE PROPAGATION OF TREES BY CUTTINGS IN SUMMER. 341 



in the creation of shoots. This circumstance respecting the different 

 operations of immature and mature leaves upon the surrounding air pre- 

 sented itself to the early labourers in pneumatic chemistry. Dr. Priestley 

 noticed the discharge of oxygen gas, or dephlogisticated air (as it was 

 then called), from mature leaves ; Scheele making, as he supposed, a 

 similar experiment upon the young leaves of germinating beans, found 

 these to vitiate air in which they grew. These results were then supposed 

 to be widely at variance with each other ; but subsequent experience has 

 proved both philosophers to have been equally correct. 



I possess many young seedling trees of the Ulmus campestris, or 

 suberosa, or glabra, for the widely- vary ing characters of my seedling 

 trees satisfy me that these three supposed species are varieties only of a 

 single species. One of these seedling plants presented a form of growth 

 which induced me to wish to propagate from it. It shows a strong dis- 

 position to aspire to a very great height with a single straight stem, and 

 with only very small lateral branches, and to be therefore calculated to 

 afford sound timber of great length and bulk, which is peculiarly valuable, 

 and difficult to be obtained, for the keels of large ships ; and the original 

 tree is growing with very great rapidity in a poor soil and cold climate. 



The stem of this tree near the ground presented, in July, many very 

 slender shoots about three inches long. These were then pulled off and 

 reduced to about an inch in length, with a single mature leaf upon the 

 upper end of each ; and the cuttings were then planted so deeply in the 

 soil, that the buds at the bases of the leaves were but just visible above 

 the surface of the soil. The cuttings were then covered with bell-glasses 

 in pots, and put upon the flue of a hothouse, and subjected to a temper- 

 ature of about 80. Water was very abundantly given ; but the under 

 surfaces of the leaves were not wetted. These were in the slightest degree 

 faded, though they were wholly exposed to the sun ; and roots were 

 emitted in about fifteen days. I subjected a few cuttings, taken from the 

 bearing-branches of a mulberry-tree, to the same mode of management, 

 and with the same result ; and I think it extremely probable that the 

 different varieties of camellia, and trees of almost every species, exclusive 

 of the fir tribe, might be propagated with perfect success and facility by 

 the same means. 



Evergreen trees of some species possess the power of ripening their 

 fruit during winter. The common ivy and the loquat are well known 

 examples of this ; and this circumstance, combined with many others, led 

 me to infer that the leaves of such trees possess in a second year the 

 same, or nearly the same power, as in the first. I therefore planted, 



