186 BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 
simple protostele in three of the species, M. dareicarpa, M. sub- 
falcata, and M. trichoidea. In these the xylem strand is only a 
few cells thick. In M. paradoxa the stele is a simple siphonostele 
with a tiny ring of xylem and with the phloem apparently only 
outside. 
Monogramma may well be considered as the ‘“ Amphioxus” 
type for vascular plants, and as such deserves thorough study and 
a place in any future course in the comparative morphology of 
vascular plants. 
3. EVIDENCES OF RECAPITULATION IN THE VITTARIEAE 
In a paper entitled ‘‘Juvenile kelps and the recapitulation 
theory,”* R. F. Griggs has drawn attention to the fact that 
botanists have generally accepted and applied the theory of re- 
capitulation to interpret plant phylogeny without attempting to 
test its truth. Griggs directed attention also to the objections that 
have been raised against the theory by several zoologists. In his 
study of the kelps, he reached the conclusion that these objections 
are not well founded and that there is shown by these plants 
distinct evidence of recapitulation. I wish here to consider 
briefly the case of the parallel venation series furnished by the 
Vittarieae, in order further to test the application of the recapitula- 
tion theory. 
Most of the objections appear to be built around the assump- 
tion that, since whenever a new species is produced its germ cells 
must contain the means of reproducing the new character, the 
whole ontogenetic history of a new form is on this account neces- 
sarily different from that of the parent form. Those who accept 
this assumption explain parallel series as due to necessity, that is, 
the organism in its growth repeats stages like the adult forms of 
its ancestors because such stages are structurally or physiologically 
necessary. According to this objection it should be necessary only 
to show that in some cases the ontogeny repeats stages that are not 
necessary to the attainment of the later form. 
Griggs described stages in the growth of certain of the kelps, 
to which the argument of necessity would not seem to apply. 
Numerous such examples have been noted in the animal kingdom 
and there appears to be another well-defined example of a similar 
*Am. Nat. 43: 5-30; 92-106, 19009. 
EE Sars lea ae ed ae 
