730 On the Natural Succession of the Dicotyledons. [November, 
Stylobasium.”’ On the same principle the Portu/acacee have been 
very closely assimilated to the Cactacee, with which they are 
found to agree in an astonishingly large number of characters, 
including that of the irritability of the stamens. Again the Dro- 
seraceé and Saxifrageé are now known to be closely allied fami- 
lies, as their physiognomy would indicate. And strange as it 
may at first appear, there is little doubt that the Crucifere are 
related to the Ouagracee by natural affinities more or less close. 
Further investigations from the same point of view will doubtless 
enable us to go much farther in discovering the true affinities of 
dicotyledonous plants. 
_ It is undoubtedly the special function of the floral envelopes, 
as it is of the ovary, to protect the germ, and the degree of this 
protection is the most reliable index we have. to the degree of 
advancement in vegetal life. The means employed in securing 
this end in the Dicotyle are two-fold: first, the relation in which 
the calyx stands to the ovary; and second, the character of the 
inner envelope or corolla. Botanists, while they have not ignored 
either of these essential characteristics, have generally placed 
more weight upon the second than upon the first, although for 
the purpose named the first has doubtless been of equal service 
to plants. 
From the hypogynous to the perigynous, and from this to the 
epigynous calyx-tube, there is certainly a steady progress in 
the direction of protection, and the advance of the calyx towards 
the more complete enveloping of the ovary may be regarded as 
indicating an equivalent advance in organization. In Dr. Lind- 
ley’s great work on The Vegetable Kingdom, this was made the 
leading character, although in his earlier works he had followed 
the system of Laurent Jussieu; and Prof. Julius Sachs in his 
Text Book of Botany, though in most respects making an entirely 
new departure in botanical classification, places the Rosacee@, Ona- 
gracee, Myrtacee, and other strictly epigynous families at the ` 
__. head of the system as representing the highest type of develop- 
ment. 
The classification by divisions, on the other hand, professes to 
give special prominence to the corolla as an index of progress, 
but how obscure the notion of any direct advantage to be derived 
r it to the plant must have been with the founders of that YE 
lon, Hi , Histoire des Plantes. 
