443 

 CHAPTER HI. 



ENATION. 



Under the above heading are included certain forms 

 arising from excess not of growth, but of development, 

 and consisting in the formation of supplementary lobes 

 or excrescences from various organs. 



The new formations are not due either to a repe- 

 tition or to a partition of any organ, but are out- 

 growths from others previously formed. 



In prohfication and in multiplication the adven- 

 .titious structures are of independent origin. In fission 

 the new developments grow simultaneously with the 

 older ones, of which, indeed, they are mere repetitions. 

 Moreover, in fission the supplementary lobes do not, 

 in general, project in a plane different from that of 

 the original structure, at least in the first instance, 

 though their direction may ultimately become changed. 



In enation the new growth projects from a previously 

 formed organ after it has attained to considerable size, 

 or even after its ordinary proportions have been attained, 

 and it sprouts out from the beginning in a plane which 

 is at a considerable angle to that of the parent organ, 

 and it is sometimes of a different structure from it, 

 and has different functions to fulfil. 



Many of the instances that occur of scales project- 

 ing from petals, as in Gainjophyllece, Sapindacew, &c., 

 the coronal filaments of passion-flowers, the cup of 

 Narcissus, the appendages that beset the segments of 

 the perianth in Lilium landfoliumy and other similar 

 growths, may be referred to a like process. In many 

 cases this has been proved by a study of the develop- 

 ment of the flower, from which it appears that the 

 growths in question are developed subsequently to the 

 formation of the ordinary floral whorls. It is requisite, 

 however, to be cautious in pronoimcing upon the exact 



