384 Bower . — The comparative examination of the 
actually no systematic importance have gone too far 1 . The 
whole argument of this paper is based on comparison of 
meristems : it has been shown that the progressive characters 
of the meristems run parallel with other systematic characters 
of the Filicineous series, and accordingly they must themselves 
be recognised as having a systematic value. The fault in 
dealing with meristems as systematic evidence has been the 
abuse of them : that is, however, no sufficient reason for 
ignoring entirely their systematic value. 
Not only are the meristems of the higher members of this 
series more bulky, and the external surface less strongly 
curved, but they are also notable for their extremely 
watery character, their very thin cell-walls, and the re- 
latively large size of the individual cells. These characters 
mark the meristems out as badly nourished, and they 
present a most striking contrast to the small- celled, densely- 
protoplasmic and largely-nucleated meristems of the Pha- 
nerogams, notwithstanding that in respect of their segmentation 
they approach them. It may even be suggested that the 
poverty of the tissue and the size of the cells composing 
it may have a connection as cause and effect, the substance 
necessary for the formation of more numerous walls and 
nuclei not being at hand : and reflections such as these would 
lead us on to consider whether the presence of an apical cell 
with a regular segmentation may not have its origin in some 
phenomena of nutrition not yet clearly recognised. We might 
with some show of probability assume that the regularity of 
segmentation depended upon the regularity of supply of wall- 
forming substance from the several sides of the meristems. 
Such regularity of supply would be most easily maintained 
where the whole apex is of small size, while in the larger apices 
the stream of nourishment would be less likely to converge 
equally from all sides upon the central point, and irregularity 
of construction would be the result : this is in accordance 
with experience, for, speaking generally, the smaller apices of 
the Filicineous series have as a rule a single initial, while the 
1 Compare Goebel. Sachs’ Arbeiten II , p. 451. 
