Sporangium-bearing Organs of the Lycopodiaceae. 53 
L. cernuum is thought by Treub 1 to show a primitive type of 
embryology, and an examination of the prothalli of various species 
has also led both Treub and Lang 2 to look upon this species as 
primitive. They compare its prothallus first with L. inundation 
and secondly with that of Phylloglossum. It has been shown above 3 
that an examination of the sporophylls of L, cernuum and L. 
inundatum led me to compare the two species, and it also appears 
to me that the sporophylls of Phylloglossioid with their short 
dorsal outgrowths resemble those of L. inundation. The presence 
of a protocorm and protophylls in all three forms is necessarily of 
great interest, 5 and the absence of these in the simpler types is 
quite consistent with the theory of the reduced nature of the latter. 
Bower 6 states that the embryo of L. selago very quickly forms 
short assimilating leaves, and thus its early nourishment is provided 
for without any necessity for the formation of an underground 
protocorm with protophylls. It would seem far more natural to 
regard the protophyll as an organ useful to the old types with 
underground prothallia, but lost in the later forms, than as an 
organ evolved for special purposes from a sterilised sporophyll. 
Similarly, notwithstanding Bower’s evidence for the origin of 
all the smaller leaves of a Lycopodium from sporophylls by 
sterilisation, it does not seem absolutely necessary to accept his 
interpretation of his facts. It is by no means certain that the 
presence of an arrested organ in any position indicates that a fully- 
developed organ was ancestrally present in that position. 8 In 
other words, if L. selago is derived from the more complextypes by 
an extension and simplification of the spore-producing area, we 
should reasonably expect more primoidia to be formed than would 
become functional. 
The study of the development of the sporangium does not 
throw much light on the question as to which position is the more 
primitive. The origin rather near the axil of the young sporangia 
of L. cernuum 9 cannot be regarded as of any great importance 
since it is easy to see that the later position is brought about by 
the lengthening of the sporophyll axis. The development of the 
1 Treub; 1884 and 1888. 4 p. 42., also Bower, 1908, p. 315. 
s Lang, 1899. 6 cf. p. 51. 
* p. 50 and p. 52. 0 Bower, 1901, p. 249. 
* cf. Goebel, I., p. 60. We must “guard against considering all 
arrested organs as being descended from organs which were 
developed in the ancestors of existing forms.” 
a PI. III,. Fig. 7. 
