Genus Statice as represented at Blakeney Point. I. 269 
of the palisade cells ; the average thickness is 0*488 mm. as compared 
with 0*448 mm. in the narrow-leaved lateral plant. 
The sand plants show slight differences in the development of the 
palisade, only two layers of which are present on the upper surface, and 
usually only one on the lower, but the individual elements are deeper than 
in the typical form (Text-fig. 19, B). 
Culture exercises a marked influence on leaf structure, for the plants 
Text-fig. i 7. Selereides from the 
petiole of S. binervosa. A and C from 
culture plant ; B and D from a narrow- 
leaved lateral plant. A and B = 
transverse sections ; C and D = longi- 
tudinal sections, x 170. 
Text-fig. iS. Selereides from 
the leaf sheath of S.binervosa, narrow- 
leaved plant. A, transverse section ; 
B, longitudinal section, x 220. 
grown from seed have a bifacial leaf, while those at Blakeney are iso- 
bilateral. As is shown in Text-fig. 19, c, the palisade on the upper surface 
is only two layers deep, and the spongy tissue with large intercellular 
spaces is well developed. 
This development of the spongy mesophyll in the culture form is 
undoubtedly to be related to the absence of the complex of factors acting 
on the shingle plants. The chief of these are the heat radiation from the 
hot surface of the shingle during the summer months, and the restricted 
water-supply of the habitat ; the removal of these allows of the production 
