1898] THE ORIGIN OF GYMNOSPERMS 155 
the conclusion that heterospory was attained independently by 
several lines. To put into the same genetic group all hetero- 
Sporous pteridophytes would be regarded as a morphological 
absurdity. If heterospory appeared independently in several 
lines, the same conclusion must be reached in reference to its 
natural outcome, the seed, and the polyphyletic crigin of the 
spermatophytes becomes extremely probable. 
This increases the perplexities of phylogeny, but it broadens 
its horizon, and introduces another possibility. To continue the 
same illustration, in our search for the origin of seed-plants we 
have narrowed attention to the existing heterosporous pterido- 
phytes, when some of the spermatophyte groups, as for example 
the gymnosperms, may represent an entirely distinct line in 
which heterospory and then the seed appeared, and may not be 
related directly to any existing heterosporous pteridophyte. In 
such a case we are permitted to look to some group of living 
homosporous pteridophytes as possibly containing the best liv- 
ing representatives of the group from which gymnosperms have 
been derived. 
With all these possibilities in mind, 1 wish to discuss the 
phylogeny of the gymnosperms, not so much to reach a clear 
phylogeny, as a clearer understanding of the complexity of the 
problem, and the uncertainty of conclusions. This is a field in 
which no one can afford to be dogmatic. 
THE ORIGIN OF GYMNOSPERMS. 
From Hofmeister’s classic researches to the discovery of 
Symnosperm spermatozoids by Hirase, Ikeno, and Webber, the 
fact has become increasingly apparent that gymnosperms are 
very closely related to pteridophytes. It was natural, for a 
time, to regard gymnosperms as phylogenetically intermediate 
between pteridophytes and angiosperms, for it was not easy to 
believe that such a structure as the seed appeared in more than 
one genetic line; but it is probably not going too far to say 
that there is now no serious opposition to the view that the 
Symnosperm and angiosperm lines are genetically independent. 
