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Lady Isabel Browne. 
the absence of a strobilus in the former may, or may not, be 
primitive. But the most important difference between the Selagi- 
nellaceae and the Isoetaceae is that the former have biciliate and 
the latter multiciliate spermatozoids. As biciliate spermatozoids 
are only known in Selaginella and the Lycopodiaceae among 
Pteridophyta, there is a general presumption that the multiciliate 
ones of Isoetes, though exceptional in the phylum, are the more 
primitive ; but the relative primitiveness of the multiciliate type of 
spermatozoid will be best discussed later in considering the affinities 
of the phyla. The secondary growth in thickness of Selaginella 
spinulosa offers a mere analogy with that found in Isoetes , for the 
details of the mode of growth are different. Heterospory may 
also have arisen independently in the two orders. It does, however, 
seem possible that the monarchy of certain roots of Selaginella 
may be a primitive character retained from a very distant ancestor, 
common to it, Isoetes and the Lepidodendracese. The reasons for 
this are that it is a very rare condition among recent plants, but 
one prevalent among the Palaeozoic Lycopods, and that there is no 
reason to believe that Selaginella has undergone any reduction, as 
all available evidence tends to prove that the genus is on the up¬ 
grade of evolution. 
The order of the Lycopod'iaceae contains but two genera, Lyco¬ 
podium and Phylloglossum. In considering their structure, the 
first vexed question that arises is : Is the protocorm primitive and 
its absence in the larger number of species of Lycopodium due to 
their reduction, or is it a later development of the embryo of 
Phylloglossum and of some species of Lycopodium ? This so-called 
protocorm is a tuber, which appears in Phylloglossum to replace 
the true stems, and from which, in Lycopodium, the true stem arises 
later. Professor Bower at one time considered The protocorm a 
primitive organ (5); but he has since abandoned that view and now 
regards the presence of a protocorm as a recently acquired 
character and does not regard the protocorm as being the precursor 
of the leafy stem of the Pteridophyta. In his latest publication he 
maintains that the embryo Lycopod seems prone to parenchymatous 
swellings and that the foot and protocorm are of this nature. He 
continues : “ A genus which shows two types of parenchymatous 
swellings in two distinct types of embryo, while both are absent from 
other species of the genus, cannot be expected to have ever had one 
of these as a constant feature in its ancestry. This consideration 
makes me doubt any general application of the theory of the “ proto- 
