iv KEY AND FLORA 
may be found worth while, in the case of some Umbellifere, 
Boraginacee, and Composite, to collect fruit during the sum- 
mer before it is to be used, preserve it either dry or in pre- 
servative fluid, as may seem best, and use it with freshly 
collected flowers in the determination of species. 
No systematic work with seed plants can be of much use 
unless the teacher takes constant pains to bring out the idea 
of actual relationship by descent among the forms studied, 
and to show, in the simpler cases available, some of the steps 
of evolution. The beginner must not be allowed to suppose 
that the flora which he is using contains more than a small 
fraction of the total number of plants even in the families 
treated. He must be made to realize that the Rudiacee, for 
instance, of which he has fourteen species described, really 
number as many as 4500 species, and the Composite, instead 
of mustering a few dozen strong, number in all at least 12,000 
species, For such comparisons Engler’s Syllabus der Pflanzen- 
familien will be found to contain the most recent and compact 
summary. 
A somewhat complete (phanerogamic) flora of the student’s 
region should be constantly in use. For this purpose the 
author prefers to all others the seventh edition of Gray’s 
Manual of Botany, For the convenience of those who may 
find it necessary to use Britton’s Manual of the Flora of the 
Northern States and Canada, the generic name used by Britton 
will generally be found in parenthesis after the name sanc- 
tioned by the Vienna code. In cases where Britton’s genus 
covers only part of the genus as given in this book, a state- 
ment to that effect is made, as on p. 186, —B. Fl. species 4 
(Naumburgia). For suggestions about literature see Bergen 
and Davis, Laboratory and Field Manual of Botany, p. 230. 
The novice should find a good deal of help in understand- 
ing the structure of some of the more difficult flowers and 
fruits in the illustrations which accompany several families. 
Most of these have been redrawn for the present edition by 
Mr. E. N. Fischer of Boston. 
J.Y.B. 
CAMBRIDGE, MAssACHUSETTS 
