OCTOBER 8, 1897. ] 
ease could be made out for priority of the 
sporophyte; in which event the conclusion 
would need to be inverted, the foliage leaf 
would be looked upon as a sterilized sporophyll. 
This would be perfectly consistent with the 
correlation demonstrated by Professor Goe- 
bel’s experiments, as also with the interca- 
lation of a vegetative phase between the 
zygote and the production of spores.” In 
another place he says: “To me, whether 
we take such simple cases as the Lycopods 
or the more complex case of the Filicineze, 
the sporangium is not a gift showered by a 
bountiful Providence upon pre-existent foli- 
age leaves; the sporangium, like other 
parts, must be looked upon from the point 
of view of descent ; its production in the 
individual or in the race may be deferred, 
owing to the intercalation of a vegetative 
phase, as above explained ; while, in certain 
cases at least, we probably see in the foliage 
leaf the result of the sterilization of sporo- 
phylls. If this be so, much may be then 
said in favor of the view that the appear- 
ance of sporangia upon the later formed 
leaves of the individual is a reversion to a 
more ancient type rather than a metamor- 
phosis of a progressive order.” 
As I have endeavored to point out in 
another place, if a disturbance of these 
correlative processes results in the transfer- 
ence of sporophyllary organs to vegetative 
ones on the sporophyte ‘‘ why should there 
not be a similar influence brought to bear 
on the sporophyte, when the same function 
resides solely in the gametophyte, and a 
disturbing element of this kind is intro- 
duced? To me there are convincing 
grounds for believing that this influence 
was a very potent, though not the only one 
in the early evolution of sporophytic assim- 
ilatory organs. By this I do not mean that 
in the Bryophyta, for example, injury to 
the gametophyte would now produce dis- 
tinct vegetative organs on the sporophyte, 
which would tend to make it independent 
SCIENCE. 
549 
of the gametophyte. But that in the bryo- 
phyte-like ancestors of the pteridophytes 
an influence of this kind did actually take 
place, appears to me reasonable. 
‘“‘ In the gradual passage from an aquatic 
life, for which the gametophyte was better 
suited, to a terrestrial existence, for which 
it was unadapted, a disturbance of the cor- 
relative processes was introduced. This 
would not only assist in the sterilization of 
some of the sporogenous tissue, which was 
taking place, but there would also be a ten- 
deney to force this function on some of the 
sterilized portions of the sporophyte, and 
to expand them into organs better adapted 
to this office. As eruptions in the mass of 
sporogenous tissue took place and sporo- 
phylls were evolved, this would be accom- 
panied by the transference of the assimila- 
tory function of the gametophyte to some 
of these sporophylls.” 
Because sporophytie vegetation is more 
suited to dry land conditions than the game- 
tophytie vegetation, it has come to be the 
dominating feature of landareas. Because 
the sporophyte in the Pteridophyta and 
Spermatophyta leads an independent exist- 
ence from the gametophyte, it must pos- 
sess assimilasory tissue of its own, and this 
is necessarily developed first in the ontog- 
eny, but it does not necessarily follow, 
therefore, that the foliage leaf was the pri- 
mary organ in the phylogeny of the sporo- 
phyte. The provision for the development 
of a large number of spores in the thallo- 
phytes, so that many may perish and still 
some remain to perpetuate the race, is laid 
hold on by the bryophytes where the mass 
of spore- bearing cells increases and becomes 
more stable, for purposes of the greatest 
importance. Instead of perishing, some of 
the sporogenous tissue forms protecting 
envelopes, then supporting and conducting 
tissue, and finally, in the pteridophytes and 
spermatophytes, nutritive and assimilatory 
structures are developed. Nature is prodi- 
