474 BOTANICAL GAZETTE [JUNE 
we may choose only those pertaining to function. On the other hand, we 
are also justified in classifying the tissue systems according to phylogenetic 
principles, but this is not the most logical method. 
These statements are also of importance in showing the advance actually 
made in this subject during the past twelve years. Twelve years ago bota- 
nists were unwilling to relinquish the idea of the unity of the so-called fibro- 
vascular bundle, and still regarded the views of Schwendener on the primary 
function of the thick walled cells of the monocotyledons with a certain degree 
of suspicion. All this is changed, and in all our recent text-books in which 
this subject is treated, the complete bundle is spoken of as consisting of 
stereom and mestom, and the elements of the former are described as 
mechanical or supporting cells. Thus the truth of the first principle upon 
which physiological anatomy was founded is fully recognized and admitt 
y all. 
The first chapter of Haberlandt’s book contains a full and modern treat- 
ment of the typical plant cell, a description of plant tissue, and a classifica- 
tion of tissue systems according to the anatomical physiological principle. 
The second chapter treats of tissues in general and the relation of meri- 
stems to lasting tissues, and here we find a departure from the interpretation 
usually given to the developmental processes of the apical region. In all 
higher plants, at a greater or less distance from the apex, the uniform primary 
meristem cells differentiate into several distinct building tissues or meri- 
stems. These at first show no difference of outer or inner meristems, except 
the mere topographical one and the histological difference between strand- 
tissue and ground parenchyma. Regarding the function of the lasting tissue 
which is to be developed they give no hint. These primary meristems are 
not necessarily connected with any special kind of apical growth as regards 
their origin or arrangement. They may be found in plants having only a 
single apical cell, also in those with several initial cells. That is, three 
distinct meristems, which Haberlandt names protoderm, procambium, a 
ground tissue, may be found in the apical regions of plants from the moss 
upward. He states that since the time of Hanstein’s investigations many 
plants have been examined which do not show a separation into the three 
distinct meristems, plerome, periblem and dermatogen, and that the manner 
of apical growth in the phanerogams i is subject to too great variation to allow 
the selection of a single type hing a general law. 
oh The acca chapters treat of the nia tissue systems. The plan in 
__ each case is to explain first the advantages which the plant derives from the 
System under consideration, and then to give a clear and full description of 
_ its elements and their relations to other parts of the plant. A aot : 
_ graph in each chapter is devoted to the system as it llophytes, 
and its developmental history forms the concluding ue of each 
_ chapter, re ption system where such an exposition | 
