200 Mr. Knight on the Reproduction of Buds. 
and light. In the beginning of April, I observed many small 
elevated points on the bark of these roots, and, removing the 
whole of the cortical substance, I found that the elevations 
were occasioned by small protuberances on the surface of the 
alburnum. As the spring advanced, many minute red points 
appeared to perforate the bark : these soon assumed the cha- 
racter of buds, and produced shoots, in every respect similar 
to those which would have sprung from the organized buds of 
the preceding year. Whether the buds thus reproduced derived 
any portion of their component parts from the bark or not, I 
shall not venture to decide ; but I am much disposed to believe 
that, like those of the potatoe, they sprang from the alburnous 
substance solely. 
The space, however, in the annual root, between the medulla 
and the bark is very small ; and therefore it may be contended 
that the buds in these instances may have originated from the 
medulla. I therefore thought it necessary to repeat similar 
experiments on the roots and trunks of old trees, and by these 
the buds were reproduced precisely in the same manner as the 
annual roots : and therefore, conceiving myself to have proved 
in a former Memoir,* that the substance which has been called 
themedullary process does not originate from the medulla, I must 
conclude that reproduced buds do not spring from that substance. 
I have remarked in a Paper, which you did me the honour 
to lay before the Royal Society in the commencement of the 
present year, that the alburnous tubes at their termination 
upwards invariably join the central vessels, and that these 
vessels, which appear to derive their origin from the alburnous 
tubes, convey nutriment, and probably give existence to new 
* Phil, Trans, of 1803. 
