5 1 M. G. Sykes. 
fairly easy to derive such a form as L. inundatum, and then by 
increase in complexity to arrive at L. cernuum, but on this view it is 
hard to form an intelligible hypothesis as to the relations of 
Lycopodium with its fossil allies. For, although the external 
resemblances between L. cernuum and Lepidodendron suggest a 
relationship between these two plants, yet if we regard this as 
the most recent species of Lycopod, it can only be nearly related 
to Lepidodendron if that genus be still more recent in origin. 
The simpler Lycopods are alone in having sessile sporophylls 
bearing axillary “ foliar ” sporangia. Bower regards this character 
as primitive, not only in the genus Lycopodium, but in the 
Pteridophyta as a class. But there is little comparative evidence 
for such a view ; indeed recent work has made it almost incon¬ 
ceivable that the genus Lycopodium is to be regarded as more 
primitive than the larger strobiloid Pteridophytes. 1 
It is almost as difficult to consider this position of the 
sporangium as primitive in the genus itself. For we must then 
suppose Lycopodium to be derived from some such form as 
Spencerites 2 by reduction of the sporophyll axis and a consequent 
simplification of the sporophyll. Then by a shifting of the 
sporangium and elaboration of the sporophyll the more complex 
species could be evolved. Here, once more we have a sporophyll 
which may be aptly compared with that of Spencerites, but the 
comparison is only an analogy, and the petiole of the sporophyll, 
—the structure found between the cone axis and the point at 
which the sporangium pedicel takes its origin—is not necessarily of 
the same morphological nature as the apparently homologous 
axial structure in the same position in Spencerites, Lepidodendron, 
etc. This conclusion may seem somewhat forced, but it appears to 
me to be the only logical outcome of a belief in the primitive 
nature of the simple Lycopods, if any attempt is made to compare 
them with fossil genera. 
Theory of Reduction. 
(a ) Anatomical and Developmental evidence. A belief in the 
reduced nature of the simpler types of Lycopodium is gradually 
gaining ground, 1 and would no doubt find still more adherents 
were it not for the weighty evidence collected by Bower in favour 
of his “ sterilisation theory.” 
1 cf. Scott, 1907, p. 175, and Tansley, 1907. 
2 Berridge, E. M., 1905. 
8 cf. Scott, 1907, p. 173. 
