ABORTION OF SPORANGIA 163 
cases of abortion “ objectively we see nothing more than that cell-divisions 
occur, that a rudiment appears; thus strictly speaking we observe that 
something develops, not that something is reduced: this may become a 
gland, an emergence, or what not. It is comparison, and usually the 
comparison with other species and genera, etc.—that is, the type-method,— 
which teaches that it is a reduced organ, and what is its special category. 
Whenever the same comparative method leads even to the assumption 
of a complete suppression, where no rudiment of the organ is seen with 
the bodily eye, in my opinion that is, in point of fact, no more than one 
step further along the same course.” This is the position which should 
be the foundation of a correct view as to abortion, or even complete 
suppression of parts: it is currently accepted, and put in practice in the 
morphological treatment of the Angiospermic flower, and it is now high 
time that it should be applied equally to the Pteridophytes, where it has 
probably played a very important part. In the Pteridophytes too little 
attention has hitherto been paid to such subjects, and notably observations 
of arrest of sporangia, or of spore-producing organs, have been neglected. 
It is the isolation of many of the genera, and the paucity of species in 
some of the most important of them, which has stood in the way of 
their detailed comparison in this respect, and consequently arguments from 
arrest have not taken their proper place in the morphology of the 
Pteridophyta. But the argument to be founded on an imperfect sporangium 
at the base of a strobilus of Lycopodium, or on the abortive fertile spike 
of an Ophioglossum seated in the position normal for the fully developed 
part in other individuals, species, or allied genera, is precisely the same 
as that on an imperfect pollen-sac or ovule, or on a stamen or carpel in 
Flowering Plants. Further, a comparison as regards the presence or absence 
of spore-producing parts in species evidently related to one another may 
lead to the conclusion that sporangia entirely unrepresented at the 
present day were probably borne upon ancestral forms: the line of 
reasoning being the same as that in cases of hypothetical complete sup- 
pression of floral parts. It will presently be shown that such hypothetical 
suppression of spore-producing parts may be held accountable for changes in 
balance of the vegetative and propagative regions in the Pteridophytes, and 
be recognised as having led to an increasing prominence of the vegetative 
system in the course of their evolution. 
The Lycopodinous type, being represented by numerous species of 
essentially similar construction, lends itself well to such comparative 
treatment, while the comparison is the more pointed owing to the definite 
relation of one sporangium to each subtending leaf, which arrangement, 
with very few exceptions, is the constant rule for the fertile regions of 
these plants. In all known Lycopodinous types a sterile leafy region, 
of greater or less extent, precedes the fertile region in the life of the 
individual plant. In many species of Lycopodium, and especially in those 
which have the vegetative and fertile regions less clearly differentiated, 
