IOWA ACADFMY OF SCIENCES 
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probably originated in some manner. As instances may be citetf 
Cladonia coccifera, where the variety stemmatina should stand for the 
species and Cladonia pyxidata, where the variety neglecta is the prevail- 
ing form from which the other varieties given may have been evolved. 
But there is no need of multiplying such instances of bad taxonomic 
work. We should bring to bear every particle of light the ecologist, the 
morphologist, the evolutionist, the physiologist and the workers in tax- 
onomy can give us and attempt to bring about a better state of affairs. 
De Vries has told us that systematists have succeeded in dividing tax- 
onomic species into real elementary species in certain seed-plants, and we 
may hope to make some progress along this line in lower plants, at least 
among lichens. In order to do this we need not cast aside all the good 
methods employed by systematists, and resort to experimental methods 
solely. Indeed, the method outlined by C. B. Davenport and J. W. 
Blankiuship in a joint paper, “A Precise Criterion of Species,” may well 
be followed. In studying lichens as elsewhere, we describe a new specips, 
not knowing whether it stands at a “center of variation” or not, and 
only a critical examination of large numbers of individuals will enabla 
us to establish modes (centers of variation), the type specimen fre- 
quently not being thus related, but being in reality a variety. We surely 
need to know for practical working purposes, these centers, the ranges 
of variation and the degree of isolation. And, though such study may 
seldom bring us to other than taxonomic species, it is necessary to a 
study of these and will surely bring our taxonomic species to correspond 
more nearly with elementary or biological species. We must agree also 
upon some chief-differentials before we can hope for any stability in 
taxonomic results. We must likewise as surely cease to place so much 
stress upon the “historic type”, which may not be a true species in any 
sense, and seek the true “specific type”. And it is along the line of such 
statistical studies as those of Blankinship, Davenport and Weldon that 
the best results are to be expected. We should approach the study 
without prejudice as to its relationships to the question of evolution, 
resting assured that he who has sufficient knowledge of a group oi 
plants to apply statistical methods on a wide scale stands in a fair way 
to solve some questions extremely vexing to students of taxonomy, at 
the same time standing good chance of aiding materially in the establish- 
met(t of many true biological species. This method will also tend to 
do away with “splitting” and “slumping” without adequate study. 
The questions of individual variation, partial variation, progressive 
evolution, retrogressive evolution, degressive evolution, unit characters, 
probable mutating species, relative stability or plasticity of species, cor- 
relative variations, latency of characters, etc., are all more or less 
capable of study in lichens and doubtless among other lower plants also. 
With the recent researches, tending to establish sexuality among 
lichens, we may reasonably expect mutations to occur. Yet, this granted, 
