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, 



