Sporangium-bearing Organs of the Lycopodiaceae 51 
has been usual to regard the simpler types as primitive, and this 
view, which is supported by Bower' and others, will be considered 
first. 
Theory of Progression. 
(aj. Anatomical and Developmental evidence. Bower regards L. 
5 ^/ao-o , 2 with its elongated, branched strobilus, as the most primitive 
form of Lycopod, and from such forms he thinks others, with a 
more restricted spore-producing area, were derived by means of 
“ sterilisation of sporophylls.” In L. Selago, the distribution of the 
sporophylls in fertile whorls, 3 alternating with sterile ones, and also 
the presence of abortive sporangia in the axils 2 of some of the 
leaves of the sterile whorls, appears to support this theory. 
Strasburger, writing in 1873, 4 looked upon the Lycopodian sporangium 
as a product of the main stem, axial in nature, which has become 
shifted on to the sporophyll by later growth, but is actually the 
morphological equivalent of an axillary bud. The relative 
positions of the sporangia in the young and old stages in L. selago, 5 
give support to this hypothesis. Examples of axillary buds in this 
genus are found in the bulbils of L. selago and its near allies, and 
have been regarded as evidence of the primitive nature of these 
species. 
The position of Phylloglossum has been a question of some 
difficulty. Its simple structure, to which it owed its first name of a 
“ permanently embryonic form of Lycopod,” 6 is now no longer 
looked upon as primitive. 7 
Its protocorm and protophylls seem to connect it most closely 
with the Rhopalostachya, especially with the Inandata and Cernua 
from which it seems probable it may have been derived by 
reduction. 8 Bower considers now that the protophylls may not be 
primitive, but are merely a vegetative adaption, and hence he 
regards them as abortive sporophylls, 0 but it is extremely difficult to 
agree with him in this. In Phylloglossum, the last of the proto¬ 
phylls is sometimes smaller than the rest and is looked upon as an 
intermediate stage, while in L. cernuum and L. inundatum the 
protophylls are never sharply marked off from the sporophylls. 
(b.) Comparative evidence. From the simpler Lycopods it is 
1 Bower, 1894 etc. 6 Bower, 1885; also 1894, p. 361. 
2 Bower, 1901, pp. 246-249 and 1908, 1 Bower, 1901. 
p. 711. 8 Engler and Prantl, Teil I., Abt. 3, 
3 Bower, 1894. p. 582. 
4 Strasburger, 1873. 0 Bower, 1901, p. 228. 
6 PI. III., Fig. 1. 
