98 BOTANICAL GAZETTE [AUGUST 
The third part deals with resin canals. Two reasons are alleged 
for thinking them to be features of the ancestors of araucarians: 
(1) Though they are practically absent from living araucarians, 
“interesting vestigial resin canals appear in the vascular supply of 
the lowermost abortive cone scales, attached to the peduncle of the 
cone, and die out before the cone scale supply leaves the wood of 
the peduncular axis.” (2) Traumatic resin canals occur in the 
wood of some mesozoic woods which the author assigns to the 
Araucarineae because of the lack of the bars of Sanio and the pos- 
session of a modified type of pitting. The pitting in the Arau- 
cariopitys type, as has already been pointed out, is very little like 
that of araucarians and very much like that of abietineans, as are, 
in fact, its other characters. The Brachyoxylon type is rather more 
reminiscent of araucarian affinities but still not beyond challenge. 
The fourth part treats of the foliar trace and the pith, and pre- 
sents a final summing up of conclusions. In regard to the leaf traces 
-and pith the conclusions are: (1) “This persistence of the leaf trace 
[that is, in mesozoic forms] seems to be a characteristic of all woods 
of the true Araucarioxylon type, and, as has been particularly 
indicated by THISTLETON-DYER (66) and SEWARD (54), is likewise a 
feature of the trunks of the living genera Agathis and Araucaria.” 
(2) In the Brachyoxylon type from the Cretaceous, which is more 
abietinean in the rays, pitting, and in the formation of traumatic 
resin canals, the traces persist for a short time only. (3) In the 
seedling axis of Agathis australis the leaf trace is less persistent. 
(4) The leaf trace is more persistent in Araucaria Bidwilliit than 
in A gathis australis, the former of which is assumed to be the more 
primitive type. (5) It follows from the preceding that persistent 
leaf traces are not an ancestral feature of the Araucarineae. (6) In 
regard to the pith I am not at all sure that I apprehend clearly 
JEFFREY’S position. He records the usual presence of sclerotic 
diaphragms in the pith of mesozoic forms, and finds them absent in 
the pith of the seedlings and cones of living forms. Sclerotic 
nests are said to occur in the latter, perhaps as a vestige of the 
diaphragms of the earlier forms. He says further that ‘‘it is more- 
over obvious that medullary diaphragms are equally characteristic 
of both the older Araucarineae and of the Abietineae living and 
