CLASSIFICATION OF PLANTS. 217 
century who has most contributed to the general adoption of 
4 natural families. His “Essai sur les Properties des Plantes” is 
_ celebrated for the knowledge which it displays of the comparative 
_ physiological and physical action of vegetables, and the physical 
' organisation which naturally connects certain plants as a group. 
His “Prodromus Systamatis Naturalis regni Vegetabiles,” especially 
_ the latest edition by his pupils and his son, is also a wonderful 
_ work for the extent and precision of its details. 
In our own country, from the days of Ray, we have always had 
zealous followers of the science of botany, more especially in the 
class which may be called field botanists. Withering, Sir Edward 
Smith, and hundreds of followers more or less eminent, employed 
their leisure in the fascinating and healthy pursuit of species, and 
perhaps the most valuable contributions to science are the detailed 
descriptions of species, with their habits and habitats, which 
___ have enriched our botanical literature. Nor was the study of the 
_ physiology of plants—a science which may be said to owe its 
_ existence to the researches of Grew and Malpeghi— neglected. 
= To the former belongs the merit of having pointed out the differ- 
_ ence between seeds with one and seeds with two cotyledons, on 
which Ray founded his system of classification. : 
co The German botanists have always been distinguished for their 
_ patient and laborious investigations, and it was reserved for the first 
of Germans, the poet Goethe, to effect the last great revolution that 
as the ideas of botanists have undergone. In 1790, shortly after the 
_ @ppearance of De Jussieu’s “Genera,” he published a pamphlet on 
the “ Metamorphosis of Plants.” At this time the functions of the 
Organs of plants were supposed to be pretty well understood. 
: Goethe had probably in the course of his reading stumbled upon 
_ the notion which has existed from the times of Theophrastus, that 
_ Certain forms of leaves were mere modifications of others whose 
_ 4ppearance was very different ; a doctrine which Linnzeus seems 
to have entertained at one time, as he speaks in his “ Prolepsis 
_, antarum” of the parts of a flower being mere modifications of 
leaves whose period of development was anticipated. Goethe 
ans. Cee +. ae Se ee 
‘ 
ae 
5 
a | ay -P this theory, and demonstrates that the organs to which 
e many different names are applied, namely, the bracts, calyx, 
rela, Stamens, and pistil, are all modifications of the leaf; the 
