CHAP. II. OIECUMNUTATION OF SEEDLINGS. 67 



CHAPTER II. 



GENERAL CONSIDERATIONS ON THE MOVEMENTS AND GROWTH OF 

 SEEDLING PLANTS. 



Generality of the circumiratating movement Radicles, their cirouin- 

 nutation of service Manner in which they penetrate the ground 

 Manner in which hypocotyls and other organs break through the 

 ground by being arched Singular manner of germination in Megar- 

 rhiza, &c. Abortion of cotyledons Circumnutation of hypocotyla 

 and epicotyls whilst still buried and arched Their power of 

 straightening themselves Bursting of the seed-coats Inherited 

 effect of the arching process in hypogean hypocotyls Circumnuti- 

 tion of hypocotyls and epicotyls when erect Ciicumnutation of 

 cotyledons Pulvini or joints of cotyledons, duration of their 

 activity, rudimentary in Oxalis corniculata, their development 

 Sensitiveness of cotyledons to light and consequent disturbance of 

 their periodic movements Sensitiveness of cotyleddns to contact. 



THE circumnutating movements of the several parts 

 or organs of a considerable number of seedling plants 

 have been described in the last chapter. A list is here 

 appended of the Families, Cohorts, Sub-classes, &c., 

 to which they belong, arranged and numbered ac- 

 cording to the classification adopted by Hooker.* 

 Any one who will consider this list will see that tho 

 young plants selected for observation, fairly represent 

 the whole vegetable series excepting the lowest 

 cryptogams, and the movements of some of the lattei 

 when mature will hereafter be described. As all tho 

 seedlings which were observed, including Conifers ; 

 Cycads and Ferns, which belong to the most ancient 



* As given in the ' General System of Botany.' by Le Maout and 

 recaisne, 1873. 



