XLIII] MOEPHOLOGY OF CONES 117 



supply of the double cone-scale is, however, not constant even in 

 the same cone, and in Araucaria Bidwillii 1 each cone-scale is 

 supplied by two separate strands from the vascular axis though 

 in other species a single bundle enters the cone-scale and divides 

 later. It would appear, therefore, that the single or double origin 

 of the lower normally orientated bundles and of the upper set of 

 inversely orientated bundles is far from constant, and the data 

 derived from anatomical study do not afford a satisfactory means 

 of determining the morphological nature of the cone-scales. It is 

 held by Jeffrey and his school that the Abietineae represent the 

 oldest members of the Coniferales and that the Araucarineae are 

 a more recent development, the apparently single cone-scale of 

 Araucaria and Agathis being derived from the double cone-scales 

 of the Abietineae. Some botanists, e.g. Vierhapper 2 , while 

 believing that the seminiferous scale of the Abietineae is an organ 

 belonging to an axillary shoot subtended by a bract-scale and that 

 the cone-scales of other Conifers are also double structures, whether 

 or not externally divided, regard the Araucarineae as earlier in 

 origin than the Abietineae. If the cone-scales of the Araucarineae, 

 to take the extreme type, are in origin double and homologous 

 with the obviously double cone-scales of the Abietineae it is more 

 logical to regard the Abietineae as the precursors of the Araucari- 

 neae. The evidence afforded by fossils in my opinion lends strong 

 support to the greater antiquity of the Araucarineae, and I venture 

 to believe that no adequate reasons have been given for regarding 

 the cone-scales of the Araucarineae as other than simple leaves 

 bearing ovules. If, as seems probable, the Coniferales are mono- 

 phyletic in origin the cone-scales of the different families are in 

 all probability variants of a common type and, in opposition to 

 the view which is most in favour, I regard the double cone-scales 

 of the Abietineae and the corresponding organs of other Conifers 

 which afford evidence of a double structure as derivatives of a 

 simple form of sporophyll strictly comparable with the sporophyll 

 of a Lycopodium,, the placenta! outgrowth assuming an increasing 

 degree of individuality in the different lines of evolution illustrated 

 by various types of strobilus. It is noteworthy that the transition 

 from foliage leaves to megasporophylls in the Araucarineae is 

 1 Worsdell (99). 2 Vierhapper (10). 



