ON THE EVOLUTION OF DINARDA. 71 
began at an earlier date, and has attained, owing to the great 
difference of the hosts, the genera Formica and Stenamma, a 
much greater divergence between the adaptation forms in 
question. The same thing can also be shown for the tropical 
genera Fauvelia and Allodinarda, Wasm. 
As I have previously remarked, it would be certainly wrong 
to conclude that the evolution of new species and genera has been 
effected in other ant-guests and Termite guests along the same 
path of a quite gradual variety-and-race-evolution, as in Dinarda. 
For the guests of the protected type, to which Dinarda belongs 
in a great measure, other biological principles of adaptation are 
in force than for the guests of the Symphile type (=relations of 
friendship) and the mimicrytype. Together with the fluctuating 
variation we must always take into consideration the possibility 
of the building of new forms through mutation. Without 
entirely excluding Natural Selection, I believe further, in the 
case of guests of the Symphile type, we must attribute* great 
weight to Friendly Selection as a factor in evolution. 
* See on this ‘ Biologie und Entwickelungstheorie,’ 2 Aufl. 9 Kap., 
especially pp. 219 ff., 230, 259 ff. ° 
