360 Origin of Each Species Considered Separately. 



The above mentioned cross 0. lata X 0. semilata did 

 not give any particularly remarkable result; amongst 105 

 seedlings there were 39 lata, 2 nanella, 2 ohlonga^ and 1 

 alb id a, whilst all the rest were 0. Lamar ckiana. These 

 forms and the proportions in which they occur are the 

 same as those which 0. lata produces when crossed with 

 other species. These figures give little support to the 

 supposition, which is improbable on other grounds, that 

 O. semilata is a hybrid or perhaps an intermediate form 

 between 0. lata and 0. Lamarckiana. 



§ i8. OENOTHERA NANELLA. (OENOTHERA LA- 

 MARCKIANA NANELLA.) 



In view of the great importance which attaches to 

 a satisfactory distinction between species and varieties 

 it seems worth while to go a little closely into the differ- 

 ence between Oenothera nanella^ and the other new spe- 

 cies.^ 



The new species, other than nanella, which have 

 arisen in my experimental garden find no analogues either 

 in other species of the same genus or anywhere else in 

 the vegetable kingdom. Each constitutes a new and 

 distinct type and is, without question, to be regarded as 

 an elementary species. 



Varieties are distinguished from these in popular 



'^Oenothera nanella, or the Dwarf Evening Primrose, often called 

 the dwarf for short, is a constant form. The term dwarf is often 

 used to signify the smallest individuals, presented by fluctuating 

 variability, which are of course of an entirely different nature. For 

 information on such dwarfs see P. Gauchery, Recherches sur le 

 nanisme vegetal, Ann. sci. nat. hot., 8 Serie, T. IX, 1899, pp. 61-156; 

 and also D. Clos, Du nanisme darts le regne vegetal, Acad. Sciences 

 Toulouse, T. XI, 1389. 



^ For further details see the second volume of this work. 



