8 PREFACE. 



on a plant are alike, and yet every branch springs 

 from a phyton. The point is that any phyton is ca- 

 pable of making a new plant, and the characters of 

 that new plant will be very markedly determined by 

 the conditions under which it grows. The phyton is 

 simply the unit of asexual propagation as the seed is 

 of sexual propagation (see the contrasts of the keime 

 and the knospen in Mobius' recent "Beitrage zur 

 Lehre von der Fortpflanzung der Gewachse"). The 

 word bud might be substituted for phyton, but that 

 word now has two or three technical uses; and, more- 

 over, it is not always necessary that actual buds be 

 present in order that phytons shall grow when made 

 into cuttings or grafts. "Potentially, every node and 

 internode of the plant is an individual, for it pos- 

 sesses the power, when removed and properly cared 

 for, of expanding into what we call a plant, and 

 of perfecting flowers and seeds and of multiplying 

 its kind" (page 83). The phyton is not a morpho- 

 logical or structural unit. It is the smallest part of 

 root, stem or leaf which will grow when severed, and 

 make an independent plant. 



A fuller consideration of the species -dogma (see 

 Essay IV.) was published as "The Philosophy of 

 Species -Making" in Botanical Gazette for last De- 

 cember. 



L. H. BAILEY. 



Ithaca, N. Y., 



March 4, 1897. 



