lii BOTANY. 
for tlie w'liole 24 hours and making it the basis of a calculation of the daily 
loss of the plant, the first mentioned specimen of Artemisia appears to have 
exhaled 9 ounces of water daily, or an amount equal to three-eighths of 
its weight. Even in the last trials later in the season, when leaves and stems 
had probably their fullest dryness and hardness, with one of the most waxy 
and scurfy of the Ohiones^ and moreover under atmospheric conditions more 
favorable for the plant, the loss was at least half as great. 
Notwithstanding therefore the apparent want of moisture in the soil, it 
must be the reservoir from which vegetation draws its entire supply. The 
loose character of the deposits which till the valleys and form the foothills 
not only allows a ready passage for the roots to any necessary depth but 
especially, through the force of capillary attraction, compels the retention 
or absorption from beneath of a sufficient amount of water for the tem- 
porary extraordinary needs of these perennial species. And this natural 
resource of the vegetation must be taken into account as greatly favoring the 
possibility of the successful introduction of orchard, vineyard or other tree- 
culture in these at present desert territories. 
Conclusion. The present condition of the Botany of our western flora 
is such as to render a satisfactory determination of the species of any col- 
lection a matter of some difficulty. The descriptions of many of the genera 
and species are scattered, without clue to guide in the search for them, 
through numerous volumes of government reports and periodical publications 
of this country and of Europe, not always readily accessible. The synonomy 
is somewhat confused, and in the case of various genera revisions are much 
needed, with a collation of all the existing materials, a work which is going 
on under the hands of Dr. Gray, Dr. Engelmann and others. 
In the examination of the present collection use has been made almost 
exclusively of the herbariums of Dr. Gray, Dr. Torrey and Prof Eaton, which 
are the richest in original and authenticated specimens of western species 
and to which, their accompanying liljraries, free access was most gener- 
ously given with every fiicility for study and comparison. So far as the 
work has been performed by others the names carry their own sufficient 
authority. As for the rest it can only be claimed that care and effort have 
not been spared to secure correctness. 
The trouble experienced in making available the authorities upon western 
species gradually suggested the extension of the Catalogue beyond the usual 
