Of Vegetation, 341 
ftrongathletick conftitution: For when grow- 
ing nature is deprived of proper materials for 
thispurpofe, then is (he under aneceflity of 
drawing out very {lender threads of life, as is 
too often the cafe of young growing perfons^ 
who by indulging in ipirituous liquors, or o- 
ther exceifes, do thereby greatly deprave the 
nutritive dudile matter, whence all the dif. 
tending fibres of the body are fupplied. 
Since we are by thefe Experiments aflured 
that the longitudinal fibres, and fap veflelsof 
wood in its firft year's growth, do thus diftend 
in length by the extenfion of every part $ and 
fince nature in fimilar productions makes ufe 
of the fame or nearly the fame methods : 
Thefe confiderations make it not unreason- 
able to think, that the fecond and following 
years additional ringlets of wood are not 
formed by a merely horizontal dilatation of 
the vefiels j for it is not eafy to conceive, how 
longitudinal fibres and tubular fap-vejfiels 
flhould thus be formed 5 but rather by the 
fhooting of the longitudinal tubes and fibres 
lengthways, from thofe of the laft year's wood, 
whereby there is a free communication main- 
tained between thefe, and the fap-veflels of 
all the preceding year's growth. The obfer- 
vations on the manner of the growth of the 
Z 3 ringlets 
