10 NOTES AND COMMENTS [suLY 
was discussed in the last volume of Natural Science, had dictionaries 
sent, if not hurled, at him, we think that he was right—for this is an 
age of compromise—in sticking to kainogenesis, and he seems to have 
Gegenbaur and other great authorities on his side. But to those who 
believe that kainogenesis is a term for an empty conception, the reading 
cenogenesis will doubtless seem preferable, for the German lexicon states 
that «xevds means (1) leer, (2) vergebens, (3) eitel, (4) miissig, (5) aus- 
geleert. But, after all, the gist of the matter is rather that we should 
be sure that there is such a distinction as that between kainogenetic 
and palingenetic, before we become excited in regard to our spelling of it. 
Flora of Sand Dunes. 
THE flora of sand dunes has always been of great interest to botanists 
from the number of peculiar species which it offers, and also—especi- 
ally more recently—from its remarkable oecological importance. The 
climatic and soil conditions under which it exists are so extreme in 
character, and vary so continually, that it offers a suitable field for the 
study of many problems dealing with the interaction of plants and 
their environment. Partly from this reason, and partly because of the 
absence of any complete study of dunes beside fresh water, Dr. H. C. 
Cowles of Chicago University has just published (Bot. Gaz. xxvii. 1899, 
Feb. to May, Fig. 26) an elaborate account of the general relation- 
ships of the dune vegetation of the shores of Lake Michigan. This 
paper is the first of a series on the subject, and treats of the geogra- 
phical aspect. The extent of the whole area considered is great, but 
most attention is paid to the south-east coast of the lake, where the 
dune formation attains its maximum development—being largely due 
to the action of north-west winds. 
In comparing those dunes to these familiar to observers in Europe 
the resemblances are much more conspicuous than the differences. It 
is remarkable how well many of the descriptions might be applied to 
the dunes around the British coast, if only the names of the species of 
plants were replaced by those of their European equivalents. Thus on 
the beach, where we should find Cakile maritima, Dr. Cowles records C. 
americana. On the loose dunes of both continents -Ammophila 
arundinacea is the dominant and most important sand-binding grass. - 
The plant associations in both cases include those of the xerophytic 
ridges, the intermediate swamps, and the mesophytic woods. In this 
country Salix repens fringes the travelling dune, in Michigan it is 
replaced by S. glaucophylla and S. adenophylla; here Pinus sylvestris 
and Betula alba are the dominant trees on the fixed dunes, there it 
is Pinus banksiana, Betula papyrifera, Thuya occidentalis, Fraxinus 
americana, etc. Many of the observations made by Dr. Cowles with 
