rors] BURLINGAME—ARAUCARIANS 3 
was at once foliar and spore bearing; (3) this foliar organ became 
differentiated into two parts, (a) a reduced spore-bearing part and 
(b) a foliar part, somewhat after the fashion of an Ophioglossum — 
leaf; (4) these compound organs were aggregated into cones; 
(5) in the process of cone formation the foliar portion was gradually 
reduced and the ovuliferous (spore-bearing) portion was increased; 
(6) in the pine cone the spore-bearing portion is the ovuliferous 
scale, in Araucaria it is the ligule, and in many other plants ligule- 
like outgrowths are to be explained in the same manner (47, pp. 
320-323). He offers the following arguments in its support: 
(1) it harmonizes a great variety of facts; (2) this gradual develop- 
ment of the ovuliferous scale and reduction of the bract is in accord 
with geological history, because it is only in the Abietineae that the 
distinction between scale and bract is comprehensible, and they are 
later and more specialized forms than the earlier Araucariae and | 
Taxodiae; (3) the brachyblast theory requires us to think of the 
ancestral forms as having less compact strobili and with cone scales 
more like a leafy shoot, and this is directly opposite to the historical 
fact. We shall return in a later paragraph to the question of 
how much of this evidence is still pertinent after the presentation 
of the more recent views. 
In 1905 CampBELL (8) stated his opinion that “as both the 
pollen tube and seed formation are but further developments of 
heterospory, it is quite conceivable that these might have arisen 
independently more than once. The close resemblance between 
the conifers and the lycopods, especially Selaginella, probably 
points to a real relationship. The strobiloid arrangement of the 
sporophylls, as well as the development of the prothallium and 
embryo, are extraordinarily similar, and it is not unreasonable 
to suppose that this is something more than accidental. The 
strong resemblance between the method of the secondary thicken- 
ing of the stem in the arborescent fossil Lycopodineae, and that 
of the conifers, as well as the anatomy of the leaves, suggests a 
real affinity. It is known that some of these bore seeds, which 
in structure and position may very well be compared to those 
of typical conifers.’’ He reaffirmed this opinion in less precise 
terms in 1911 (9). 
