He 
FROM THE STANDPOINT OF AN IDEALIST. 45 
in order to give point to their statistical treatment we will assume the truth 
of the implication of Engler’s system that they represent a genetic sequence 
commencing with the Monocotyledons and terminating with the Sympetale. 
It would have been possible to discuss this matter at considerable length; 
but as the treatment is purely tentative a few general remarks will be here 
sufficient, and the columns of the tables (II., IV.-VIII.) will be allowed 
largely to tell their own story. 
It will be at once noticed that whilst the six primary groups of the 
Angiosperms behave with comparative uniformity in matters concerned 
with the bi-eleavage of the land-mass, as reflected in their distribution 
in the Old and New Worlds, they often present marked contrast in their 
responses to the differentiation of the climatic zones. Thus, to take their 
behaviour in the first case, the proportions of families occurring in both the 
east and west hemispheres vary only between 62 and 77 per cent. (Table II.) ; 
and if we limit the comparison to the families of world-wide distribution, 
termed cosmopolitan in the table, the percentages range only between 
21 and 33 (Table VII.). We find a like agreement in the proportion 
of families confined either to the Old or to the New World. Thus, the 
percentage of families restricted to the eastern hemisphere varies only 
between 12 and 24 and of those peculiar to the western world only between 
ll and 14 (Table IL). This conformity is remarkable when we reflect that 
in small groups of this kind we can only appreciate general approximations 
or marked deviations. The similarity in behaviour on the part of the six 
primary groups respecting the distribution of their families in the eastern 
and western hemispheres is quite independent of the proportion of aquatic 
and sub-aquatic families in each group, which is as high as 30 per cent. for 
the Monocotyledons and as low as 2 per cent. for the Sympetalze (Table V.). 
Yet this similarity in behaviour disappears when we regard the response 
made by these six primary groups to the differentiation of the climatic zones. 
As indicated in Table V., they display great variety in the appropriation of 
their families by the tropical and temperate zones. Thus Groups C and D 
of the Archichlamydez are the most tropical; and Group B and the 
Sympetale are the least tropical; whilst the Monocotyledons and Group A 
stand between. On the other hand, the Monocotyledons are by far the least 
temperate of all the groups, which is to be associated with the fact that 
a much larger proportion of the families are in a transition state—that is, are 
equally divided between the zones—than is the case with the other groups. 
Then again Group A is in these respects the most average of the six 
primary groups, approaching nearest in its behaviour to that of the 
Dicotyledons in the mass and nearer still to that of the Angiosperms. It 
comes closest to the Incomplete of Bentham and Hooker, a result to be 
expected since the two equal-sized groups hold about two-thirds of their 
families in common ; whilst the group of the Incompletz in its response to 
