FROM AN OLD STANDPOINT. 



171 



reason to suppose that the distribution of the Gentianese in 

 Miocene times was substantially ditl'erent from what it is now. 

 As concerning the possibility of putting a limit to this retro- 

 gression, he " does not think that any good grounds could l3e 

 given for denying the existence of even the more specialised 

 Gentianei^i in the Cretaceous epoch, whilst the Ur-Gentmn (the 

 hypothetical anemophilous parent type) may be dated back 

 almost as much further as probabilities permit us to carry the 

 existence of flowering plants." Professor Huxley's temerity 

 was Homeric, since not only did his method of dealing with the 

 genera on purely genetic lines in^'olve the fate of the accepted 

 arrangement of the family, but he extended his conclusions at a 

 bound to the plant-world in general, and terminated Ms paper 

 with the warning that a revision of taxonomy and distribu- 

 tion from the point of view of the evolution doctrine would 

 hardly fail to revolutionise both. 



It will thus be seen that on its biological side there is nothing 

 original in the theory advocated by me in this paper. Though 

 Huxleyan, it is not JJarwinian, as will immediately appear. 



The ijossihility of the development of the same form in different 

 loccdities. — It has already been explained why Professor Huxley 

 made no effort to determine the home of the Gentians. 

 According to his views, this ancient family had differentiated 

 from a primitive type in such a manner that he considered it 

 probable that not only the larger tribal groups, but also the 

 genera could have originated independently in different localities. 

 In this connection, it should be noted. Professor Huxley came 

 into line with Dr. Engler, whose work on the history of the 

 development of the plant-world,* he had been recently reading. 

 If we postulate, as was done by Professor Huxley, a primitive 

 generalised type of a family, we are compelled to admit that in 

 its earlier stages the differentiating process might follow similar 

 directions in different localities. A tribe, and at times even a 

 genus, might thus arise in more than one region ; and if the 

 primitive type were universally distrilnited, we might have the 

 same tribes and genera originating on opposite sides of the globe. 

 But we should be straining the argument if we endeavoured to 

 urge that this was the general rule. Xaturally, the chances in 

 favour of such an occurrence would decrease with the progressive 

 differentiation of the primitive type. It would be probable 

 with the tribe, possible with the genus, and almost impossible 

 with the species. 



Versuch einer EnticicHungsgescldchte dcr Pflanzcmrelt, 1879-82. 



