22 GLEASON: SOME APPLICATIONS OF THE QUADRAT METHOD 
typical of the association as a whole. In the latter case, and in all 
cases of verbal description, the result unconsciously and unavoid- 
ably embodies the author’s idea of the conditions, rather than the 
actual and impersonal facts, in that conspicuous species may be 
emphasized although possibly relatively unimportant, while 
important but comparatively inconspicuous species may be 
neglected. While the quadrat method is by no means a panacea 
for all these difficulties, its proper combination with verbal 
description and photography does much to aid the observer in 
securing a thorough knowledge of the association and in more 
satisfactorily expressing its structure in terms intelligible to his 
readers. The merit of the method lies not merely in the actual 
results which it affords but also in the deductions from and 
application of these results. 
While quadrats may be of any chosen size, a single square 
meter is probably most frequently used. In the list quadrat, a 
simple list is prepared of the species included within it. In the 
count quadrat, the number of individuals of each species is also 
determined. Both of these are of value as a method, but are of 
little use in expressing results. For the latter purpose, the map 
quadrat is by far the most useful. A chart is prepared on a 
suitable scale, usually 1 to 10, and the location of each individual 
plant noted upon it. Other sorts of quadrats may be made for 
special purposes, concerning which reference may be made to the 
various works by Clements (1904, 1905). 
The structure of a vegetational unit depends upon the species 
represented, determining the flora; on the relative number of 
individuals of each, determining by their form, size, and habit the 
appearance of the vegetation; and on the total number of indi- 
_ viduals, determining the density of the vegetation. 
The use of a chosen quadrat in representing this structure 
depends absolutely on the theory of the homogeneity of the ass0- 
ciation, which in turn depends on a number of factors (Gleasom, 
1917, p. 471). Given a uniform physical environment, the — 
migration of some species over the whole area requires consider- | 
able time and interferes with the uniformity until it is accony: 
plished, so that young associations are always less uniform than 
old ones, while in open associations migration may continue for a 
