THE FLORA OF NORTH AMERICA. Joe 
can 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 lifetime ; and it was only 
recently, in the spring of 1878, that I succeeded in bringing 
out, in a changed form, another instalment of the work, com- 
pleting the Gamopetale. 
In the interval I had made two year-long visits to Europe 
for botanical investigation, the first partly relating to the bot- 
any of the South Pacific, the second wholly in view of the 
North American flora. And since this last publication still 
another visit — the fourth and we may suppose the last — of 
the same character.and the same duration, has been success- 
fully accomplished. 
The serious question, in which we are all concerned, arises, 
whether this work can be carried through to completion, and 
the older parts (wholly out of print and out of date), reélabo- 
rated, — I will not say by my hands, but in my time, or soon 
enough to render the whole a reasonably full and homogene- 
ous representation of the North American flora, as known in 
this latter part of the nineteenth century. And it brings us 
to consider why the undertaking to which so much time has 
been devoted should be so slow of accomplishment. 
If this slowness is a constant wonder and disappointment to 
most people interested in the matter, I can only add that it is 
hardly less so to myself. It is a constant surprise —if one 
may so say — that the work does not get on faster. 
Of course the undertaking has become more and more for- 
midable with the enlargement of geographical boundaries and 
of the number of species discovered. As to the increase in 
the number of species to be treated, we have by no means yet 
reached the end. The area, that of our continent down to the 
Mexican line, we trust is definitely fixed, at least for our day. 
And since we cannot be rid of the peninsula and keys of Flor- 
ida, which entails upon us a considerable number of tropical 
species, mostly belonging to the West Indies —the southern 
boundary is now as natural a one as we can have. 
The area which Pursh’s Flora covered was, we may say, the 
United States east of the Mississippi, with Canada to Labra- 
