Feb., 1909.] 
The Sporophylls of Lessoniopsis. 
439 
into main branches, floats and photosynthetic areas as in Egre- 
gia, was accomplished by sterilization and modification of poten¬ 
tial sporophylls. At first thought it might be supposed that 
Lessoniopsis, by the possession of the characters of both lines, 
should be regarded as representing a basal point from which 
both subfamilies had originated by following divergent lines of 
evolution. Such seems, however, an untenable view. There 
are none of the indications of a primitive character for Lessoniop¬ 
sis. It is, in the judgment of the writer, clearly a member of 
the Lessoniatae. The characteristic branching of that series 
is the dominant character of Lessoniopsis and gives it the form 
and structure of its adult body, while the proliferated sporophylls 
do not make their appearance until the plant has practically 
completed its development. This is in great contrast to the 
Alariatae in which the sporophylls appear very early even in the 
lowest members where their function is almost exclusively repro¬ 
ductive and is not called into activity until maturity. 
The unlooked for appearance of such a character among the 
Lessoniatae is to be considered as a striking example of the 
remarkable adaptability of the whole family of kelps by virtue of 
which we find in more than one plant structures belonging to 
lines otherwise entirely disconnected from it. This makes it 
difficult to construct a satisfactory classification of the genera 
because inconsistencies from this cause are almost unavoidable 
whatever principle of classification is used. The descent of the 
kelps seems to be a much interwoven fabric which has been sur¬ 
prisingly little divided up into narrower strands by the loss of 
plasticity by which each line is narrowed into its own special 
channel of evolution. This great variability along with many 
other features of the kelps leads to the view that the group is still 
in its youth and evolving rapidly. 
LITERATURE. 
Griggs, R. F., 1909. Juvenile Kelps and the Recapitulation 
Theory. Am. Nat. 43: 5-30. 
Reinke, J., 1903. Studien z. Vergl. Entwickelungsgeschichte 
der Lamimaraiceen. Kiel. 
