116 



obtain an affinity-group by the direct observation of natural affinity, as 

 Englee says in § 2, Snch. groups, according to liis statement'\ exisfc 

 only in species, genera, families or in series. In other words, natural affinity 

 is to be found between pne individual and another individual belonging to 

 the same species, between species and species belonging to the same genus, 

 between genus and genus belonging to the same family, between fa.mily and 

 family belonging to the same series ; but there is generally no phylogenetic 

 relation between series and series. Consequently, in his sysfcem, spacies, 

 genera, famihes are, as far as his statemenfc is concerned, arranged according 

 to their uatural affinity ; while the series are not so aiTanged. It foUows, 

 therefore, that the series are arranged, according to their degree of advance- 

 ment, or according to their simpHcifcy or complexity, or according as they are 

 primitive or reduced. His sysfcem is locally, in tliis parfc or thafc, natural in 

 the sense thafc ifc denofces a certain relafcion of blood - kinsliip or a consfcitufcional 

 resemblance ; but liis system, taken as a whole, is an arfcificial system, the 

 series of which are an-anged according to their degi"ee of advancement, or to 

 some such idea. As for the recapitulafcion theory which is given by him in 

 § 2, as a means of determining natural affinity, it is in many cases especially 

 in plants not to be rehed upon'-^ The other experimental method given by 

 him is something that can be seen only in some few special cases. He says 

 that it is necessary to ascertain afiinity through the study of the development 

 liistory. I think that is truly indispensable for finding the mutual relations 

 in the case of development ; but I think it is equally necessary that we should 

 take into account the resemblance in the adult stage ; the natural relation of 

 young forms is sometimes different from that of adult forms, so that the real 

 natural relation is only conceivable in its dynamic phase. He writes as 

 follows''^ especially for the liigher plants : — 



Dagegen sind wir bei der Feststellimg der Verwandtschaft lioherer Sippen 

 genotigt, auf indirektem Wege die natiirliche Verwandtschaft zti ermitteln, nnd 

 dabei leicht irrtiimlichen Anflfasstmgen ansgesetzt. 



1) ENGUEas, A. — Erlatiterungen, 1. c. p. 362. 



2) ScHOUTE, J. C. — Die Stelar-Theorie, p. 138 (P. Noordhoff Groningen, 1902). 



3) Engleb, A. — 1. c. p. IX. 



