527£ Or Yule on the analogy of the organs of the Embryo 
those of the economy of plants, but it is, in many cases, equally 
delusive, to apply the deductions of analogy to the distinct races 
of plants themselves ; and yet this source of error is still too pre- 
valent ; notwithstanding the meritorious discoveries of Csesalpi- 
nus, Gsertner, R. Brown, Mirbel, and lately of Cassini, in this 
fundamental part of the physiology of plants. But, surely, be- 
cause Caesalpinus discovered, that, in a great number of the seeds 
of plants, the embryo, forming, in many tribes, the body of the 
seed, included as between two shallow cups, the still unevolved 
parts of the future plant ; protecting, and, as it were, cherishing 
them ; absorbing moisture from the earth, and, as was long since 
discovered by Robert Boyle, a portion of the atmosphere*; — cer- 
tainly neither Caesalpinus, nor his successors in the present day, 
have had sufficiently correct grounds for concluding, that another 
race, including the greater part of the numerous tribes of vascular 
plants, formed on a distinct plan, in the general structure of their 
seeds, and even in their minutest germs and manner of growth, 
as well as in the structure of their stems, in short, every part of 
their economy, should yet possess in their embryo a single mono- 
cotyledon, and constitute a class on this very account. It has 
been concluded, that the Natural Method of arranging plants 
must stand or fall with the truth of this hypothesis. But, in fact, 
the natural method has no need of support from the imagination ; 
and, indeed, if it did so, it would deserve to fall. But it is time to 
come to the point in dispute; and probably the speediest method of 
ending this or any other controversy is, to appeal to the acknow- 
ledged principles of adversaries who, I presume, must admit, that 
the surest of all characters in deciding precisely the nature of any 
given organ, whether in plants or animals, is its relative position. 
Let us try the question of the existence of monocotyledons by 
this test. 
I. The true cotyledons, then, are immediately connected 
with the trophosperm, and situated, as in the seeds of the nu- 
merous tribes of Legumineae, externally with respect to all 
the other organs of the embryo, which they envelope. 
The supposed monocotyledon of Mirbel and Cassini, on the 
contrary, is not connected with the trophosperm, and is situated 
internally, with respect to these organs. 
® See the late excellent work of Mr Ellis on the Germination of Seeds. 
3 
