28 
C. E. Moss. 
vertical belts of vegetation in Armenia, thus proving, according to 
Clements (1904 : 150), that “ the concept of zonation is the oldest 
in phytogeography.” 
It was shown in the preceding section of this paper that the 
term “ formation ” has frequently been used to signify an association. 
Clements (1905: 292) has stated that “there have been as many 
different opinions in regard to the application of the term formation 
as there are concerning the group which is to be called a species;” 
and Flahault (1901 : 405) also wrote: “It is not to be marvelled at 
that several botanists, who had doubtless lost their way in this 
confusion, acknowledge having employed the word without thinking 
of its definition.” 
It is not surprising, therefore, that the development of the 
concept has proceeded along somewhat divergent lines. One such 
line has already been indicated: this was the use of the term by 
Hult (1881, etc.) and others to signify a minor though important 
unit of vegetation, a unit which is now regarded as a subdivision of 
a formation, and termed an association. A second line of develop¬ 
ment may now be traced. 
An oft-quoted passage of Grisebach (1838: 160), introducing 
the term “ formation,” is thus rendered by Clements (1905: 3):— 
“I would term a group of plants which bears a definite [“ abge- 
schlossenen ”] physiognomic character, such as a meadow, a forest, 
etc., a phytogeograpliicalformation. The latter may be characterized 
by a single social species, by a complex of dominant species 
belonging to one family, or, finally, it may show an aggregate of 
species, which, though of various taxonomic character, have a 
common peculiarity; thus, the Alpine meadows consist almost 
exclusively of perennial herbs.” It is obvious that this general 
statement of Grisebach’s early idea of the formation does not exclude 
all associations, for many of the latter “ bear a definite physiognomic 
character” and are “characterized by a single social species.” 
Hence those writers, such as Hult, who have used the term 
“ formation ” in the narrow sense, i.e., as equivalent to an association, 
are able to find some historical support for their procedure. On 
the other hand, it must be admitted that the particular units of 
vegetation to which Grisebach applied his term were almost 
invariably of greater extent than single associations. 
A review by Grisebach (1849: 339, et seq.) of a work by 
Duchartre (1844) enables one to gather the meaning which the 
eminent plant-geographer attached to the term in his earlier 
