and Ordinary Forms of Primula sinensis. 245 



are, cell for cell, larger than those of the ordinary form, and that 

 to a degree sufficient in itself, I think, to account for the greater 

 thickness of the Giant. Just the same resemblance in structure 

 and difference in size is found in other regions of the stem and in 

 the petioles of the leaves ; the difference is sufficiently illustrated 

 in the figures of the stem, and I have not thought it necessary to 

 multiply the number of figures in order to illustrate the petioles. 

 In these observations there is, I think, strong ground for the 

 suggestion that the difference between the Giant and ordinary 

 forms may be referred to a difference in the size of the cells ; 

 that is, the character of Giantness manifests itself in the cells 

 themselves and not merely in the plant as a whole. At present 

 only a suggestion can be made, for we are as yet ignorant as to the 

 extent to which individual variations among plants of the same 

 type may affect these results ; my observations have been limited, 

 for want of others, to one pair of plants. I hope in the future to 

 make a comparison between a number of Giant and ordinary 

 plants, grown, as were the pair described here, under similar 

 conditions. 



EXPLANATION OF PLATE X. 



The figures were all drawn with a Camera lucida. Figs. 1 — 6, 8, 

 and 9 were drawn with a Zeiss 2 mm. Apochromatic Obj., 18 Ocular. 

 For fig. 7 the same objective with Ocular 8 was used. Figs. 10 — 13 

 were drawn with a f in. objective. 



Fig. 1. Ordinary form; metaphase of the heterotype division in 

 the pollen mothei cell, the section being transverse to the spindle. 

 X about 3200. 



Fig. 2. Giant form; as fig. 1. 



Fig. 3. Ordinary form ; prophase of the heterotype division of the 

 pollen mother cell, x 3200. 



Fig. 4. Giant form ; as fig. 3. 



Fig. 5. Ordinary form ; later prophase (diakinesis) of the hetero- 

 type division, the chromosomes in the form of gemini. x 3200. 



Fig. 6. Giant form ; as fig. 5. 



Fig. 7. Nuclei from the layer of cells surrounding the embryo sac ; 

 the upper row from the Giant, the lower row from the Ordinary form. 

 X 1420. 



Fig. 8. Nuclei from the same layer ; the left hand row from the 

 Ordinary form, the right hand row from the Giant form. The nuclei 

 shown were the largest to be found in one section of an ovule in each 

 case. X 3200. 



