121 
wesentlichen und unwesentlichen Merkmalen. Es hat sich jedoch 
herausgestellt, da& selbst sehr wesentliche Merkmale bei den durch 
sie charakterisierten Gruppen nicht immer konstant auftreten; es 
hat sich ferner herausgestellt, da&B viele Merkmale in der einen 
Pflanzengruppe wesentlich, in der anderen unwesentlich sind, s0 
z. B, Art der Konidienbildung, Bliitenfarbe, Sekretzelleh, Sekretginge, Milchsaftsch- 
lduche, Zahl der Kotyledonen, Nebenblitter, Blattstellung, Verwachsung, von Blumen- 
blittern usw. 
In the above passage, he tells us that there are “ wesentliche” and “un- 
wesentliche ”. characteristics. Now let us consider the true meanings of these 
two terms. What are called important characteristics clearly must include 
those which were taken voluntarily or conventionally as the criteria for the 
erection of a group and for determining the limit of the latter, or those which 
come in linkage with the above qualities. In other words, they designate 
those which characterize what we had habitually regarded as a group. 
The term “ unwesentliche”’ points out those characteristics which are just the 
opposite of the above qualities. Thus interpreted, there could originally have 
been no such difference in characters as is expressed by the words “ wensent- 
liche” or “ unwesentliche.” All characters show natutal relations in respect of 
themselves, no matter whether they be taken or no§ taken as criteria or whether 
they come or do not come into linkage relations with the other features, that 
is to say, regardless of whether they characterize or do not characterize the 
conventional groups. They should all, therefore, be taken into account in any 
system denoting natural relations. 
What Enouer states in §8', may be taken as an. illustration of the 
statement that he applies the term “wesentliche” to a character that is 
helpful in justifying the present system, and that he applies “ unwesentliche ” 
to one that stands in the way of our doing so. 
His statement in §9” is in my opinion altogether impossible. For 
phylogenetic development is not a matter that can be made clear through a 
comparison of the plants of the present age; and even if it could be done, 
the difficulty would remain that the order of progression or the stage of 
development is not the same for all plants, but is possibly different for every 
1) Eyerer, A.—l. c p. XL 2) Enoier, A.—-1. c. p. XI. 
