88 ON VAPJETTF.S, KACES. SUB-SPECIES, AND SPECIES. 



subjected. In the first case, cold prevents the ])]ants from 

 running- up, and the organized matter necessary for the first 

 development of the stem, instead of getting there, remains in the 

 root. 



B. Injliience of external agents in different places in 

 modifying the same seeds ; (a) in one and the same climate ; 

 (b) in different climates. 



(a) In one and the same climate. 



Differences in the soil, degrees of exposure, moisture, may 

 affect a plant in different ways in the same climate. 



The Freneuse turnip is a remarkable example of this. This 

 variety, characterized by a reddish tinge and peculiar taste, is 

 constantly I'ejjroduced at Freneuse in a red soil, whilst efforts 

 made in many other places to propagate it from seeds collected 

 at Freneuse liave not succeeded, or if they have, plants have 

 been obtained, the seeds of which have, either in the first, or 

 at all events in the second or third generation, lost this pro- 

 perty. There are no doubt places where it would grow exactly 

 as it does at Freneuse. 



We see by this example why, in certain places where we wisli 

 to obtain individuals of certain species having any peculiarity not 

 possessed by those plants which are yielded by seed gathered in 

 the same locality, we are compelled to obtain fresh seed every 

 year from those places where the seeds do yield plants with the 

 desired properties. Thus we get from Brussels the seeds of a 

 cabbage peculiar to that place regularly every year ; and these 

 seeds, sown by us in our garden at Hay, give us exactly what we 

 want. 



Van Mons, when he removed his establisliment from Brussels 

 to Louvain, found the soil at the latter place less suitable for 

 his fruit-trees than thut of the former, and that his cherries, l)ut 

 peaches did not lose their qualities so mucli as his pears and 

 apples. 



The following statements from tlie Pomologie Physiologiq^ie 

 also illustrate the influence of locality on the quality of fruits : 

 The Besi du Quessoy is in Brittany a good pear, whilst at Paris 

 it is good for nothing ; the Bonchretien d'hiver, though excellent 

 at Paris, is uneatable in Gatinais. 



(b) Influence of external agents in different climates. 

 As we find a mere difference of locality, where the climate is 



pretty nearly the same, has so great an influence on the develop- 

 ment of plants, we should naturally expect to find this influence 

 still greater wliere the climates also differ, and we shall not be 

 surpiised to see what great modifications our conmion Eurojiean 

 plants undergo by cultivation in the Kew World. 



