92 THE CONTROL OF LIFE 



and too much partridge at the other. In any case we 

 submit that the facts warn us against being in a hurry 

 to depart from the common-sense belief that for the 

 individual, at least, peculiarities of nurture may count 

 for much. 



§ 3. Individually Acquired Modification and 

 Their Transmissibility 



On some parts of the east coast of Scotland the trees 

 are all lopsided ; the main stem bends landwards and 

 almost all the branches stretch their arms away from 

 the sea. This is the result of the strong east wind, and 

 it is a simple example of a modification. If we look at 

 the white Water Buttercup {Ranunculus aquatilis) on a 

 quiet stretch of a stream we see that most of the leaves 

 are lying on the surface and are simply lobed ; but on 

 another stretch where there is a rapid flow the leaves 

 are all submerged and cut up into green threads. This 

 is another example of a modification, an individually 

 acquired character due to a peculiarity in nurture, and 

 it is historically interesting in being one of the examples 

 Lamarck gave of the direct action of the environment. 



It should be noticed, however, that we do not know 

 to what degree a predisposition to assume filiform leaves 

 is now part of the hereditary constitution of the water 

 buttercup. A more clear-cut case would be one in 

 which a water plant not previously known to exhibit 

 cut-up leaves developed these in a swift stream. 



If a part of our skin is persistently subjected to local 

 pressure, it often gives rise to a protective thickening 



