The Laws of Mutation. 249 



it Is natural that one should occasionally be in doubt 

 over some of them ; particularly over such as happen to 

 grow between others, and have not, on that account, 

 sufficient space for their full development. I have usually 

 given these plants an additional lease of life, in many 

 cases the whole summer. They then very soon proved 

 to be a pure type ; or perhaps, to be compound forms 

 such as 0. lata nanclla, O. scintillans elliptica and so 

 forth, or, lastly, new forms altogether. But they never 

 turned out to be intermediate forms. Transitions be- 

 tween the various elementary species did not occur. 



As a matter of fact I have thought on one or two 

 occasions that I had discovered examples of such inter- 

 mediates. For example \ once noticed a plant which was 

 like O. lata in many respects but bore plenty of pollen. 

 I fertilized the plant artificially and raised 270 plants 

 from its seed. These were all like their parent except 

 for 1 % of them which were true lata, that is to say no 

 larger a percentage of O. lata than the Laniarckiana- 

 family Itself can give rise to. I have called this form 

 O. semilata (§ 17). Other cases of a similar nature have 

 been observed. 



The seed of a newly arisen form will, If sown, always 

 give rise to plants with exactly the same characters as 

 their parents : and this purity of the new form is main- 

 tained in subsequent generations. 



II. New elementary species are, as a rule, absolutely 

 constant from the moment that they arise. The seeds 

 set by an example of a newly arisen species after arti- 

 ficial self-fertilization give rise solely to plants like itself; 

 without, as a rule, any trace of reversion to its parental 

 form. 



This is equally true of O. gigas which has only arisen 



