W. Nbilson Jones 81 



the same size and considerably broader than the finest veins of D.P. 

 The reciprocals (text-figs. 24 and 25) differ from one another in the 

 greater resemblance to the seed-parent in each case. 



14. The margins of the leaves also show well-marked characters. 

 That of D.P. is c<iarsely crenate and (presumably by its more rapid 

 growth relatively to the rest of the leaf) crinkled so that it cannot be 

 made to lie flat (text-fig. 34). 



The margin of D.G. is serrate, the coarseness of the serrations 

 varying greatly in different leaves of the same plant, but always much 

 smaller than the crenations of D.P. (text-figs. 35 a and 35 h). In 

 {D.P. X D.G.) there is an intermediate condition of affairs both as to 

 size and shape of the marginal projections (text-fig. 36) : while in the 

 reciprocal these projections are rather larger and run out into long 

 points, the furrows between always forming a smooth concave curve 

 (text-fig. 37) instead of a sharp angle. 



15. Text-figs. 26, 27 and 28, 29 are camera lucida drawings of 

 the upper and lower epidermis of leaves of D.P. and D.G. 



Comparison shows that the cells of D.G. are larger and have more 

 irregular walls than D.P. The stomata of D.G. are larger though less 

 numerous than in D.P. Since D.P. has the larger leaf this is the 

 reverse of what might have been expected. 



The epidermal cells from the leaves of the hybrids are intermediate 

 in character with a slight leaning towards the female parent (text- 

 figs. 30, 31 and 32, 33). 



The epidermal cells differ so much in different leaves and different 

 parts of the same leaf that this character is somewhat indefinite, although 

 the drawings were taken as representing the average condition. 



16. Transverse sections show that the leaves of D.G. (text-fig. 43) 

 are thicker than D.P. (text-fig. 42), the average thickness in the two 

 cases being '2 mm. for D.P. and '33 mm. for D.G. Both reciprocals 

 resemble D.P. as regards thickness of leaf (text-figs. 44 and 45). The 

 greater thickness of the leaves of D.G. seems due both to the larger size 

 of individual cells and also to the greater number present. 



Discussion of results. 



It must be concluded from the above analysis of the reciprocal 

 crosses between D. purpurea and D. grandiflora that, in general, the 

 expression of any character in the hybrids is intermediate between its 

 expression in the two parents, the reciprocals differing from one another 

 in that each shows a greater resemblance to its seed-parent. 



