111 



\v*esentlichen und tinwesentlichen Merkraalen. Es hat sich jedoch 

 heransgestellt, daB selbst sehr wesentliche Merkraale bei den durch 

 sie charakterisierten Gruppen nicht immer konstant auftreten^ es 

 hat sich ferner herausgestellt, daB viele Merkmale in der einen 

 Pf lanzengruppe wesentlich, in der anderen unwesentlich sind, so 

 z. B. Art der Konidienbildung, Bliitenfarbe, Sekretzellen, Sekretg-inge, Milchsaftsch- 

 Ijiuche, Zahl det Kotyledonen, Nebenblatter, Blattstellung, Verwachsung, von Blumen- 

 blattern usw. 



In the above passage, lie tells us that there are " wesentliche " and " un- 

 wesentHche " characteristics. Now let us consider the true meanings of these 

 two terms. What are called important characteristics clearly must inchide 

 those which were taken voluntarily or conventionally as the criteria for the 

 erection of a group and for determining the Hmit of the Latter, or those which 

 come in Hnkage with the above quaHties. In other words, they designate 

 those which characterize what we had habitually regarded as a group. 

 The term " unAvesentHche " points out those cliaracteristics which are just the 

 opposite of the above quaHties. Thus interpreted, there could originaUy have 

 been no such difFerence in characters as is expressed by the words " wensent- 

 Hche" or " unwe^entHche." AU characters show natural rehitions in respect of 

 theinselves, no matter whether they be taken or not taken as criteria or whether 

 they come or do not come into Hnkage relations with the other features, that 

 is to say, regardless of whether they characterize or do not characterize the 

 conventional groups. They should ah, therefore, be taken into account in any 

 system denoting natural relations. 



What Enoleb states in §8^, may be taken as an illustration of the 

 statement that he appHes the term " wesantHche " to a character that is 

 helpful in justifying the present system, and that he appHes " unwesentHche " 

 to one that stands in the way of our doing so. 



His stateraent in § 9'^ is in my opiuion altogether impossible. For 

 phylogenetic development is not a matter that can ba made clear through a 

 comparison of the plants of the preseut age ; and even if it could be done, 

 the difficulty would remain tliat the order of progression or the stage of 

 development is not the same for all plants, but is possibly diiferent for every 



1) Engijbb, A. — 1. c. p. XL 2) Enolkr, A. — I. c p. XIL 



