270 



NOTICES OF AUTHOHS. 



It is a subject of considerable difficulty to explain 

 the cause of slender lengthened shoots in sheltered 

 situations, and short stout shoots in exposed. Sir 

 Henry solves this " excellently well" in two ways, 

 first, attributing it to shelter and exposure them- 

 selves, — " for shelter is heat, and exposure cold," — 

 and again, to an instinctive straining in the shelter- 

 ed to reach the light, of which its neighbours deprive 

 it every way but from above, and would do so there 

 too if it failed to exert itself 



We find that vegetables have long spindling 

 shoots, and wide spaces between the leaves or buds, 

 when growing in a damp, still, close atmosphere, espe- 

 cially when the plant is sickly or weak from defi- 

 ciency of nourishment, and that this happens equally, 

 whether a trailing plant being supported aloft throws 

 out depending shoots in opposition to the current 

 of light ; whether a climbing * plant runs out hori- 

 zontally along a branch or beam at right angles to 

 the light, or whether a self- supported mounting 

 plant rises in direct opposition to gravity. No 

 doubt, when the light comes from one direction, 



* We do not pretend to explain how it is, that one kind of 

 climbing plant follows the sun in its convolutions, and another 

 traverses his course. There surely cannot be any thing in a ha- 

 bit acquired in the southern hemisphere. 



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