44 PRINCIPLES OP PLANT-TBRATOLOGY. 



Yarious ways) an invagination takes place on opposite 

 sides of the head, the two meet in the centre, and 

 thus completely divide the head into two.* 



A cm-ions form of " double " daisy {BelUs pereiinis) 

 was seen which may be attributable to ring-fasciation. 

 The main capitulum consisted of three to five separate 

 small heads bunched together, but there was in this 

 case a common involucre surrounding the whole. 



A dahlia was also seen which had a triple head 

 within a common involucre. " Ring-fasciation " thus 

 appears to be nothing more or less than a process 

 whereby forking of the capitulum is attained. 



2. The Flower. 



a. Ordinary Fasciatcon. — A forked or fasciated 

 flower exhibits ji;st the same appearance and phenomena 

 as a fasciated or forked capitulum of a Composite. All 

 the same degrees and stages are met with, from that 

 in which the diameter of the flower is merely increased 

 beyond the normal, either symmetrically or in one 

 plane only (PI. XXXIII, fig. 2), a good example of 

 which was seen in a rose, to that in which two 

 or more perfectly distinct and separate flowers are 

 formed. Good instances of the first degree of fascia- 

 tion are afforded by the auricula and polyanthus, types 

 of what occur in many other flowers, in which the 

 flower becomes enlarged, and the number of members 

 in each whorl increased, so that the abnormality 

 ranges from 6-merj in the least modified flowers to 

 25-mery in flowers showing the greatest degree of 

 fasciation. These floAvers represent incipient stages 

 in the differentiation ;ind individualization of two or 

 more distinct flowers (fig. 70). So that, remembering 

 that the normal flower is 5-merous, our abnoi'mal 

 6-merous flower may be regarded as the equivalent 

 of H normal flowers, the 2o-merous flower as the 

 equivalent of five normal flowers. Dr. E. J. Salisbury 



* Reference to the diagram of this phenomenon, as it occurs in the flower, 

 given on a later page, will make its nature clear. 



