168 Gigantism in Primula sinensis 



uuder consideration, is a more massive plant, with slower growth than 

 that of the ordinary form of White Queen Star from which it arose. 

 The corolla of the Giant is about half as large again as the corolla 

 of the normal form and adjacent petals of the former either meet 

 or overlap instead of leaving a narrow space between them as is 

 the case with the normal plant. 



The overlapping of the contiguous petals is a characteristic of 

 giants both of the sinensis and stellata type of flower, and is due to 

 the fact that the oblate petals are much broader ba.sally than are 

 the more ovate petals of varieties of normal stature. In one respect 

 only does Giant White Queen Star differ from most giants. It has 

 retained the tiering habit of the typical stellata form of inflorescence. 



This example of a giant form characterised by a typically stellata 

 habit of inflorescence is not unique. Thus the Giant White Star which 

 has been investigated by Gregory (1909 and 1911) possesses also the 

 stellata type of inflorescence. Giant White Queen Star conforms in 

 all respects with the known giant races of P. sinensis. Its flowers are 

 large, of good substance, and slow to open. Its notched petals— the 

 edges of which are apt to be slightly fimbriated — are rounded in the 

 bud stage, grow slowly, and as they grow broaden basally till those 

 adjacent to one another meet or overlap. The flowers are much more 

 lasting than are those of the normal parent, and the massive stigma 

 persists for weeks if pollen be denied access to it. 



IV. A Histological Comparison of Giant with Normal 

 White Queen Star. 



The most comprehensive examination of the histological character- 

 istics of a giant form of plant is that made by Gates (ioc. cit.) in the case 

 of Oenothera gigas. 



Comparison of 0. gigas, a giant mutant of 0. Lamarckiana, with the 

 normal form from which it arose has led Gates to the conclusions that 

 the cells in the giant are conspicuously larger than in 0. Lamarckiana; 

 that the cells of certain tissues of the giant are almost exactly twice the 

 size of those in the coriesponding tissues of 0. Lamarckiana ; and that 

 the giant, 0. gigas, has double the number of chromosomes present in 

 0. Lamarckiana. 



Histological comparison of Giant and Normal White Queen Star, 

 shows at once that the f<irmer is a giant because its constituent cells 

 are gigantic. The marked difference between Giant and Normal White 



