>% 
1878.j On the Natural Succession of the Dicotyledons. 731 
tem, is shown by the order in which the divisions were arranged. 
It seemed evident to their minds that those plants which were 
wholly destitute of a corolla, the apetalous or monochlamydous 
division, should stand at the base, and thus far they were certainly 
consistent. But in placing the polypetalous division at the head 
of the system, the idea of its protecting function must have been 
quite forgotten. For unquestionably the monopetalous corolla is 
the form of floral envelope which affords the greatest protection 
to the ovary and staméns, and the more nearly this eien to 
the tubular form the more complete is that protection. The 
tinct, usually spreading, and often fugacious petals of aa 
plants are of very little service in this respect, so that, in so far at 
least as this one principle is concerned, they should certainly 
stand next above the Apetaleæ. 
In this respect too, it is true, certain monocotyledonous plants 
would take a higher rank than some apetalous and polypetalous 
Dicotylæ, their tubular perianths forming better protecting en- 
velopes. But as it is the genealogical series that the new taxon- 
omy seeks, other more fundamental characteristics must pre- 
clude all attempts to derive the Monocotyle from any advanced 
stage of the Dicotyle. 
The general truth, which is becoming more and more apparent, 
is that the floral envelopes cannot alone be relied upon to indi- 
cate the course of development of the Dicotyledons, and that for 
the natural arrangement of the families many other considera- 
tions must be taken into the account. Instead of depending 
upon any one character it is necessary to consider all the charac- 
ters together. The task, it is true, is vastly more difficult, and 
systematic botany becomes a science requiring exhaustive study, 
but the conclusions reached will ue correspondingly more 
valuable. 
One of the best checks by which the genealogical systematist 
may frequently orient himself, is what has been called the “ physi- 
ognomy” of plants. Whenever the pursuit of any particular — : 
character or set of characters is found to have brought into close _ 
proximity plants of a totally different physiognomy, it is gener- 
ally safe to conclude that the process has been carried too far; 
and on the other hand, when, as is frequently the case in the 
present system, plants having strong general resemblances have 
been widely separated, the propriety of reviewing the evidence — 
