376 
women have gladly undertaken from time to time the investiga- 
tion of difficult or of poorly-known groups, and they have almost 
without exception brought to bear upon their work every modern 
method of research. This period has been noted farther for great 
activity in similar work throughout the country. An unusual 
amount of material in the way of field-notes has also been re- 
cently accumulated, a large part of it directly in the interest of 
this work. All this material has been assiduously studied. 
Although some of the cases of species-division appear surprising, 
yet in view of the minuteness with which the authors have con- 
ducted their studies, it may well be that such criticisms as shall 
be made will possess the demerit of being based upon a lower de- 
gree of scrutiny than the determinations themselves. 
That the possibility of determining a plant by merely turning 
to a figure may induce habits of superficiality, is perhaps, true, 
though hardly so in case of such a work as this. Even in case of 
those fragmentary illustrated works which may be regarded solely 
or chiefly in the light of picture books, it is probable that the hab- 
its of observation and comparison they induce and develop more 
than counteract any such tendencies to superficiality ; but in the 
present case every influence tends to lead the student on to deeper 
examination and more scientific methods. Reference has already 
been made to the illustration of the minuter structures beside the 
general illustrations. Even more important in this direction are 
the keys to the groups, so freely furnished as to form a complete 
system. No one, having learned to use botanical language, would 
of course think of consulting the cuts until the possibilities of the 
text—that of the keys, at least—had been exhausted. Those 
others, who may at first resort to the pictures, will, doubtless, 
quickly learn that time is usually saved by a different course, and 
a study of botanical terminology introductory to the use of the 
keys will almost surely follow. If there be some to whom this 
statement does not apply, the defect may be regarded as natural, 
and displayed in spite rather than because of the character of the 
book. 
Keys, if not usually artificial, are pretty likely to accomplish — 
their purpose the better in proportion as th ey are so... Thetis 
however, in the keys of this flora an evident design of combining 
