104 SPENCER : THE AFFINITY OF DADOXYLON TO CORDAITES. 
related to the Araucaria, arid first begins to hold a prominent posi- 
tion in the somewhat scanty flora of the Permian age. But during 
the Mesozoic ages the Araucaria held a similar predominant position 
in the vegetable kingdom that the Dadoxylons held in the preceding 
Palaaozic ages. So long as Dadoxylon was regarded as a true pine it 
appeared to afford a strong argument against the theory of evolution, 
but now it has been shown that its supposed affinity with the 
pines is based entirely upon the resemblance of its wood to that of 
the Araucaria, and that the structure of the whole stem, pith, 
wood, and bark being taken into consideration, it is seen to have 
more affinity with the Cycads, as seen in Cijcas revoluta, than with 
the Araucaria ; and it is found to occupy its natural place both in the 
vegetable kingdom and in the order of its appearance in geological 
time according to the theory of evolution. 
