68 
Sinnott. — The Morphology of the 
In Cryptomeria , A thro taxis , and Cunninghamia, however, only a single 
bundle leaves the axis to supply the double appendage, but this single 
bundle, normally oriented, consists of the bract and scale systems fused. 
Its two ends soon bend upward, adaxially, and in Cryptomeria a ring of 
separate bundles is eventually formed. Only the median lower one enters 
the free end of the bract, and all the rest, forming a wide arc precisely as 
in Sequoia, represent the scale series. In Athrotaxis (Diagram 8, f) and 
Cunninghamia only a few small bundles, sometimes only one, are cut 
off from the adaxially curving ends of the original single strand and become 
oriented inversely. These bundles, which are obviously all there is left of the 
scale or axillary system, merely supply the ovules. The lamina of the ap- 
pendage, now almost entirely bract, is provided with a long row of normally 
oriented bundles derived from the main part of the original single 
strand. 
Early writers considered that a condition very similar to that of 
Cunninghamia was present in Araucaria and Agathis , and that the scale 
system was here reduced merely to the ovular bundles, the bulk of the 
‘scale’ being supplied by a wide arc of strands, normally oriented, which 
were derived from the main part of the original bract bundle. Certain 
recent investigators, notably Professor Thomson, have maintained that the 
scale in the Araucarineae is a single (aplosporophyllous) structure and not 
a double one, and that it is entirely homologous with the microsporophyll 
and the vegetative leaf. He calls attention to the fact that in this family 
there are only two series of bundles, one to the c scale \ and the other, with 
inverse orientation, to the ovule, but that in the Abietineae, Taxodineae, 
and Cupressineae, which he considers double-scaled or diplosporophyllous, 
there are three series : one to the bract ; one, inverse to this, to the scale ; 
and a third, with another inversion of orientation, to the ovule. The Podo- 
carpineae, according to this theory, have been derived from the Araucarineae 
through forms similar to Saxegothea , for conditions in this genus resemble 
those in Agathis , the bulk of the appendage being supplied by a row 
of normally oriented bundles derived from a single strand, and the upper 
series consisting of little or nothing beside the ovular supply. Dacrydium 
and Podocarpus are derived from this by the increase in comparative size of 
the ovule and by the ‘ basipetal development ’ of its vascular system, which 
eventually attains the dignity of an independent insertion on the axis quite 
distinct from that of the supply to the £ scale \ The Podocarps and Taxads 
are therefore regarded as simple-scaled forms which have developed their 
female strobilus by an amplification of that of the male, and which are 
sharply separated from those Conifers where the female cone is an axis 
bearing axillary ovuliferous short shoots. The Coniferales are on this 
supposition divided into two great groups which must have been separate 
almost since the assumption of the strobilar habit. 
