Vi PREFACE. 
temperature similar to that of their native climates. None 
of these arrangements, however, afford any means by which 
a student, in possession of a plant unknown to him, can 
discover its situation in the catalogue; and, of course, he 
is necessitated to have recourse for this purpose to the 
instruction of a living master, who may not always be at 
hand. 
With the view, therefore, of enabling a solitary student 
to refer an unknown plant to its congeners, Lobel discarded 
every other consideration than the structure of plants, par- 
ticularly of their flowers, that being the period when they 
principally attract our attention. On this foundation, he 
investigated the natural affinities of plants to each other, 
and arranged those known to him in between forty and 
fifty families, beginning with the grasses; and gave a list 
of those belonging to each family, but without determining 
any common character by which the plants of each family 
may be known; leaving this decision, in respect to the 
plants not noticed by him, to the intelligence and acumen 
of the student. Cesalpinus, Ray, Tournefort, Hermann, 
Boerhaave, and other authors, who were trained in the 
schools of logic and of the mathematics, have endeavoured 
to supply this deficiency, and to exhibit the marks or 
characters by which the several natural families may be 
recognized, and have further attempted to arrange these 
families in a regular series, so that the student, instead of 
relying upon his own conceptions of the affinity of a plant 
with those known to him, may, from a consideration of its 
structure when in a perfect state, refer it to its proper 
family, and ascertain its name if already known, or have, 
in the other case, a well grounded assurance that it has not 
hitherto been described or named by authors. 
The first scientific botanists, in consequence of their 
attempts to employ none but very obvious characters, could 
only attain their end by using a multiplicity of them, and 
this necessitated an intricate arrangement. Succeeding 
authors attempted simpler methods, by choosing a few par- 
