60 TJic Different Modes of Origin of nezv Species. 



But the large number of cases of forms preliminarily 

 described as varieties but which possibly may be only 

 variants, is one of the most considerable obstacles in this 

 inquiry. 



Linnaeus himself followed two distinct rules in sub- 

 dividing his species. According to the one the species 

 was regarded as the type from which the varieties were 

 derived ; according to the other, however, the species was 

 regarded as a collective group wdiich embraced a certain 

 number of units of equal value. The separation is sharp 

 and definite and Linnaeus w^as obviously perfectly con- 

 scious of its reality. In the derived varieties the series 

 begins with /? followed by y, 8, e etc. ; it is taken for 

 granted that the type or Forma gemiina represents the a. 

 Li a homonomous series there is no such Forma gemiina, 

 and the series of varieties therefore begins with a. 



Let us consider the two cases separately and let us 

 begin with the second. 



LiNNAEUs's homonomous varieties, a, /?, y etc., are 

 sometimes arranged in groups, and sometimes not (as in 

 Tencriiim Poliiim, Larandnla Spica, etc.). In the former 

 case the species falls into tw^o or several subspecies, each 

 of which again may include one or several varieties. For 

 instance Euphorbia exigna has two subspecies acuta and 

 rctusa, the first of which consists of one and the second 

 of two varieties. Beta vulgaris has the well-known sub- 

 species rubra and Cicia; the first of these embraces five, 

 the second two varieties. In these species there is no 

 Forma typica or Forma genuina. The variety which is 

 named first has no other priority over the others. 



In such cases the species is a group of similar com- 

 position to that of a genus and of a family ; since in these 

 no particular species or genus is regarded as the proto- 



