439 
is to be noted, also, that Nature seems to have followed in practice 
the theory by which we have explained her curious development 
of series. For example, a short willow branch seems to exemplify 
the % phyllotaxy, but a longer stem plainly shows a 2 arrange- 
ment. The plum and apple, similarly, are promoted by the care- 
ful student from the ; class to the 34 class; and the walnut and 
butternut, which we are at first tempted to consider examples of 
the 34 spiral, belong at least to the ;3, series, and the suspicion 
§TOws on us that, if we could find a perfect branch with a large 
number of leaves on it, we might ascend still higher in the range 
of spiral series. But it is of analytical value to be able to assign 
a plant to a place in one of two series, just as it is helpful to be 
able to say, “ such a leaf has from five to seven pairs of leaflets.” 
The tulip tree, oaks, hickories, staghorn sumach and alternate 
leaved dogwood (the last two being arborescent) have the 3 ar- 
fangement quite distinctly. In other instances the results were 
So conflicting, or the practical difficulties of obtaining good speci- 
mens were so great, that the summer closed before I could reach 
definite conclusions, if, indeed, it is possible to ascribe plants to . 
certain series in all instances. 
With the exception of the dogwoods, variations in phyllotaxy 
n€ver cross generic lines and seldom if ever infringe upon the limits 
of families, 
Reinke’s Discussions of Lichenology. 
By ALBERT SCHNEIDER. 
It is thought advisable to give a review of Reinke’s paper on 
lichenology, because this author is doubtless the most competent 
advocate of modern scientific lichenology. Although much of the 
author’s discussion is based upon theory and the observations of 
others, yet the papers are of inestimable value to the special student, 
and we hope that they will be collected and issued in book form. 
Meanwhile it is hoped that this review may be found useful by 
« 
those English-speaking students who can not readily avail them- 
Selves of the original communications. 
