SI 6 MODIFIED CIECUMNUTATION Chap Vl 



ledon of Trifolium striatum, in combination with that 

 of the first true leaf. Lastly, the wide distribution in 

 the dicotyledonous series of plants with cotyledons 

 which sleep. Eeflecting on these seyeral facts, our 

 conclusion seems justified, that the nyctitropic move- 

 ments of cotyledons, by which the blade is made to 

 stand either vertically or almost vertically upwards 

 jr downwards at night, has been acquired, at least 

 in most cases, for some special purpose ; nor can wo 

 doubt that this purpose is the protection of the upper 

 surface of the blade, and perhaps of the central bud 

 ur plumule, from radiation at night. 



