94 Muhlenbergia, Volume 4 
Dr. Britton, being an experienced worker in the field of 
taxonomy, has presented a very able paper. First of all he gives 
the historic side, or the opinions of eminent botanical workers 
from Linnaeus in 1751, to De Vries, in 1905. 
Linnaeus believed that “there are as many species as there 
are different forms or structures met with to-day.’ This should 
prove quite a shock to those who would have us go back to the 
Linnaean simplicity because we are describing too many species 
in these days. 
A. P. DeCandolle says: ‘‘We see, that, in order to decide 
respecting the idea of a species, an observation of many years, 
and of much accuracy, is often required; and that the cultiva- 
tion of plants, from the most different climates, in botanical gar- 
dens, is in the highest degree necessary for their discrimination.” 
Lindley calls attention to the fact that there are two kinds 
of species, the natural species and the botanical species. The 
first “is a union of individuals agreeing with each other in all 
essential characters of vegetation and fructification, capable of 
reproduction by seed without change, breeding freely together, 
and producing perfect seed from which a fertile progeny can be 
reared.” ‘These, he says, “have been ascertained to a very lim- 
ited extent,” because their determination depends upon experi- 
ment. The second, or ‘botanical species,” constituting the 
greater part, are those which are found to ‘‘agree in their exter- 
nal characters,” and they are ‘‘an assemblage of individuals agree- 
ing in all the essential characters of vegetation and fructifica- 
tion.” And he asserts that we can not pick upon any particular 
characters and say that those and those only must be the essen- 
tial ones in all cases, but “that one class of characters may be 
essential in one genus, another class in another genus; and these 
points can be only determined by experience.” ‘The determi- 
nation of species is, therefore, in all respects, arbitrary, and 
much depends upon the discretion or experience of the botan- 
” 
ist. 
