186 Gigantism in Primula sinensis 



them may give rise to zygotes characterised by minor peculiarities 

 which are the outcome of the several constitutions. 



However this may be, the origin of Giant White Queen Star appears 

 to provide an example of the appearance of a " new," dominant character 

 and is noteworthy because of the small number of cases in which this 

 form of evolution has been observed. For, as is well known, the 

 " dropping out " of a factor is common enough in the descent by 

 reduction which cultivated and wild plants are undergoing; whereas 

 the number of known examples of the appearance of new dominant 

 characters (Punnett, 1911) is much fewer and none is known in which 

 the phenomenon has, as it were, been witnessed in a pure strain. 



Second, the complete infertility of the giant when crossed either 

 with its parent or with other strains and its original relative infertility 

 on self-fertilization are remarkable and suggestive facts. 



Third and last : the phenomena of gigantism appear to have a 

 bearing on those which concern the origin and nature of certain of 

 our cultivated plants such as fruit trees and shrubs. Thus a culti- 

 vated variety of apple, pear or plum is evidently a giant with respect 

 to its fruit. It may well prove that this cell-gigantism is the origin 

 of all the differences between the large and luscious fruit of the 

 cultivated apple and the astringent puny fruit of the crab. Alter the 

 size of the cell-laboratory and the operations of that laboratory are 

 altered. Events which mark the waning of the life of the small and 

 rapidly maturing cell of the crab may never — for reasons of time or 

 space — occur in the large and slow growing cell of the apple. The 

 character of astringency would seem to have been lost by the dropping 

 out of a factor for that character ; whereas on the view now presented 

 it is only lost because under the new conditions of growth the character 

 cannot appear. How far all or most Mendelian characters depend 

 directly or indirectly on such growth acceleratory and growth inhibitory 

 factors must be left for subsequent consideration. 



Summary. 



1. A giant form of White Queen Star originated from a normal 

 strain of known pedigree. 



2. The giant arose in the course of selection-experiments made with 

 plants possessing flowers with supernumerary petals. 



3. Histological comparison indicates that the gigantism of the 

 mutant is due to that of its cells. 



