24 : BOTANICAL GAZETTE [JULY 
abietinean. He refers particularly to the absence of resin canals, 
even of the revival type, in the former, and their presence in the 
latter. The rays of the latter are thick and pitted in the fashion 
of the Abietineae, while those of the former are thin and resemble 
those of modern araucarians as well as cordaiteans. In like manner 
the pitting of the former is more extensive, more crowded and 
flattened, and with the pits mostly alternately arranged; whereas 
in the latter they are less numerous, more restricted to the ends of 
the tracheids, less crowded, and more frequently opposite. He 
contends that this is consistent either with a cordaitean or an 
araucarian ancestry for the pines, but difficult to reconcile with an 
abietinean ancestry of araucarians. 
5. VESTIGIAL STRUCTURES, RECAPITULATION, TRAUMATIC REAC- 
TIONS.—The broad transitional zone between primary and second- 
ary wood in the araucarian cone has already been mentioned as a 
remarkable parallel to the condition found in the cordaitean stem. 
The pitting in the cone is also more extensive. The pits cover the 
whole radial surface of the tracheids, are crowded and mutually 
flattened, and there may sometimes be as many as five rows to a 
tracheid. THomson remarks (70) that not only does the pitting 
in the araucarian cone resemble cordaiteans, but that “instead 
of the opposite pitting, the pitting of the cone axis and early wood 
of the Abietineae has characteristically either scattered uniseriate 
pits or biseriate ones which are alternately arranged.”’ 
A torus, characteristically present in mature wood of Abietineae 
and feebly developed in mature wood of Araucarineae, is entirely 
absent (70) in such primitive regions of the latter as cone axis, 
first-year stem wood, primary and young secondary root wood. 
They should be expected in some or all of these places if araucarians 
had descended from abietinean ancestors which possessed them. 
Bars of Sanio are well developed in the Abietineae and feebly so ~ 
in the araucarians (42, 70). They are also poorly developed in 
the primitive regions of Abietineae and in the mesozoic Pityoxyla. 
From this THomson infers that well developed bars of Sanio were 
not characteristic of the ancestors of the pine alliance. 
He also argues that, since resin canals are ontogenetically devel- 
oped from solid parenchyma and are frequently solid in the abie- 
