#3QUV9 1VC 
BOTANICAL GAZETTE. iji 
of the ensuing year to the examination of the principal herbaria, 
which I need not here specify, in Scotland (where the important 
one of Sir Wm. Hooker still remained), England, France, Switzer¬ 
land and Germany, namely those which contained the specimens 
upon which most of the then-published North American species 
had been directly or indirectly founded, especially those of Linnaeus 
and Gronovius, of Walter, of Aiton’s Hortus Kewensis, Michaux, 
Willdenow, Pursh, and the later ones of DeCandolle and Hooker. 
After my return the work made good progress; the remain¬ 
ing half of the first volume was brought out in the spring of the 
year 1840, and by tie spring of 1843 the 500 pages of the second 
volume, mostly occupied by the vast order Cumpositae, had been 
issued. But meanwhile I had in my turn to assume professorial 
duties and incident engagements,—with che result that, although 
the study of North American plants was at no time pretermitted, 
either by Dr. Torrey while he lived, or by myself, we were unable 
to continue the publication during my associate's life-time; and it 
was only recently, in the spring of 1878, that I succeeded in bring¬ 
ing «.*ut, in a changed form, another instalment of the work, com¬ 
pleting the Gamopetake. 
In the interval I had made two year-long visits to Europe for 
botanical investigation, the first partly relating to the botany of 
tixe S'mtH Pa^ ’ * *b Ameri- 
