SUMMARY 363 
SUMMARY OF THE COMPARATIVE EXAMINATION OF THE 
LYCOPODIALES. — 
The sporophyte of the Lycopodiales has now been studied compara- 
tively as regards its external form, its spore-producing members, its 
anatomy, and embryology. The conclusion arrived at from all these 
quarters is favourable to a strobiloid origin, with subsequent specialisation 
along lines variously divergent. By the comparison of known representa- 
tives of the Lycopodiales, living and fossil, certain characters have been 
recognised as relatively primitive, others as derivative: and thus a general 
idea has been obtained of a primitive type of Lycopod-sporophyte, which 
forms the basis of a theory how such a sporophyte came into being. In 
form this primitive sporophyte was probably a simple, unbranched, radially 
constructed shoot, endowed with unlimited apical growth, while local 
intercalary growth might also occur. The axis bore undifferentiated leaves, 
each of which had one sporangium associated with it in a median position. 
It was rooted at its base, but the origin of the root may be held 
to have been accessory in evolution, as it is seen to be late and variable 
in the individual development. The. internal construction of the shoot 
showed a non-medullated monostele, continuous as a cauline column to 
the apex of the axis, while the foliar strands were inserted with but shght 
local disturbance upon its periphery. Its sporangia were kidney-shaped, 
and not greatly extended radially. The primitive body thus sketched in 
its broad outlines was derived from a spindle-shaped embryo, without 
any haustorial swelling, or tuberous protocorm. The theory of the 
strobilus, as enunciated in Chapter XI., would adequately account for 
the origin of so simple a sporophyte as this, from a still more primitive 
body, with sterile base and fertile apical region, by segregation of the 
fertile tissue into separate sporangia, and by enation of sporophylls. 
The nearest living representative of such a sporophyte which has been 
adequately investigated is Lycopodium Selago ; but it is to be remembered 
that this is the only one of 39 species: of the Seéago-section of the genus 
so examined, and there are indications, derived as yet from external 
characters only, that other and more primitive types than Z. Se/ago exist 
among them: these await further investigation. The first leaves formed 
on the embryo of Z. Seago are lateral in origin, and become aerial and 
green, but are sterile: sporangia were noted by Bruchmann,’ as first 
appearing after the second branching of the axis, which, however, is 
early as compared with the other European species, though not as 
compared with the large Andean forms. Their early appearance, as 
well as the similarity of the sterile and fertile leaves, coupled with 
the evidence of abortion of sporangia in the upper region, all point 
to the conclusion that originally all the leaves were sporophylls, while 
all arose laterally upon the axis. 
lie, p. 100, 
