68 The Different Modes of Origin of new Species. 



is evidently due, in the vast majority of cases, to retro- 

 gressive development or latency, as I have already at- 

 tempted to show. 



There is a close analogy between the formation of 

 these varieties and that of certain species. The origin 

 of varieties (such as Var. hirsiitissinia, spinosissima and 

 ciliata) as the result of the intensification of characters 

 is a much rarer phenomenon. This form of variety, 

 which seems to be of very little importance in the evolu- 

 tion of the vegetable kingdom, may be called subprogres- 

 sive, and the phenomenon of its origin subprogressive 

 formation of species. 



The parallel, retrogressive, and subprogressive modes 

 of origin have this in common that they only provide new 

 combinations and do not contribute new units or any es- 

 sentially new elements to the progressive evolution of the 

 vegetable kingdom. In this respect they stand in sharp 

 contrast to progressive formation of species. 



There is another series of phenomena to be mentioned 

 here, of still less significance in the phylogeny of plants. 

 The first of these is the manifestation of old, latent char- 

 acters. A wdiole series of anomalies are so widely dis- 

 tril3uted in the vegetable kingdom, or at least among 

 flowering plants, that it is almost impossible not to as- 

 sume a common cause for them. This cause must be 

 a latent character that has arisen in some common ances- 

 tor and therefore must be of great anti(|uity. The com- 

 monest and best known example of a widely distributed 

 anomaly of this kind is that of fasciation, instances of 

 which in almost any desira])le number of species can be 

 collected in the course of a few years. It appears that 

 almost every species amongst Coni ferae and Monocotyl- 

 edons, but especially among Dicotyledons, can exhibit 



