CuAP. II. OIEOUMHUTATION OF SEEDLINGS 67 



CHAPTER tl. 



General Considerations on the Mo^ejients and Growth cf 

 Seedling Plants. 



Generality of the cirrumnutating movement — Radicles, tlieir circum- 

 nutation of service — Manner in which they penetrate the grnund — 

 Manner in which hypocotyls and other organs break through the 

 ground by being arched — Singular manner of germination in Slegar- 

 rhiza, &c. — Abortion of cotyledons— Circumnutation of hypocotyls 

 and epiootyls whilst still burled and arched — Their power of 

 straightening tlieraselves — Bursting of the seed-coats— Inherited 

 effect of the arching process in hypogean hypocotyls— Circumnutii- 

 tion of hypocotyls and epicotyls when erect — Circumnutation of 

 cotyledons — Pulvini or joints of cotyledons, duration of their 

 activity, rudimentary in Oxalis corniculata, their development — 

 Sensitiveness of cutylodons to light and consequent disturbance of 

 their periodic movements — Sensitiveness of cotyledons to contact. 



The circumnutating moTements of the several pajts 

 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 the 

 young plants selected for observation, fairly represent 

 the whole vegetable series excepting the lowest 

 cryptogams, and the movements of some of the lattci 

 when mature will hereafter be described. As all the 

 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 

 Peoalsne, 1873. 



