1I5 
of my reasons for this statement, while reviewing and criticizing EENGLER’s 
principle of natural classification and his system. 
7. REVIEW OF, AND CRITICAL REMARKS ON ENGLER’S PRINCIPLES 
AND HIS SYSTEM OF THE ANGIOSPERMS. 
a. JTENGLER’S PRINCIPLES OF SYSTEMATIC ARRANGEMENT”. 
Speaking conclusively, his principles are those of his system, but not 
those of what I shall call the natural system. I shall now take up this 
matter section by section. In the first section ENGLER says :— 
Das Streben der wissenschaftlichen Klassifikation der Pflanzen oder der botanischen 
Systematik ist zuntichst darauf gerichtet, die Pflanzenformen nach ihrer natiir- 
lichen Verwandtschaft in Gemeinschaften niederen und hiheren Grades (in 
Arten, Gattungen, Familien, Familienreihen oder Ordnungen, Klassen, Abteilungen) zu 
gruppieren.2) 
Here he speaks of “natural affinity” (Natirliche Verwandtschaft), the true 
meaning of which is certainly blood - relationship. But what systematizers can 
treat directly or are treating practically is constitutional resemblance instead 
of blood - relationship. The latter is to be found directly and exactly only in 
a census register or in such a case as ENGLER refers to in §2; it can not be 
ascertained generally. We are, therefore, obliged only to infer blood - relation- 
ship through the observations of constitutional resemblances, assuming that 
the former is in agreement with the latter (but, in reality, they need not 
agree). As the resemblances are, according to the participation theory which 
I have referred to before, manifested by the participation of genes, ENGLER’s 
affinity - group (Verwandtschaftkreis) is nothing but a collection of members 
marked by one or more genes shared in the members. The group is, there- 
fore, as I have said before, a dynamic one changeable according as different 
genes are taken as criteria. Here, it is clear that EnaLer undoubtedly 
means by affinity - group a static one unchangeable no matter in what way 
it is regarded. According to my way of thinking, the existence of such a 
definite group is impossible. Now, let us think of a case in which we could 
1) Eneren, A. — Prinzipien der Systematischen Anordnung, im syllabus der Pflanzenfamilien, 
7-Aufl. (1912) pp. VILI-—-XXIL 
2) Enorer, A.—1L oc. p. VIL 
