1895.] Anatomical and Physiological Researches. 457 
food correspondingly lessened. From the law that transpi- 
ration is more rapid on a convex than on a plane surface the 
author explains the fact that the epidermal cells of Glyceria, 
Agropyrum, and Lotus corniculatus growing in saline soils 
nounced odor, e. g., the stems of Thymus Serpyllum belong 
almost exclusively to the variety citriodorus, which is much 
ticher in volatile substances than the type. The evapora- 
tion of this volatile matter creates around the plant an atmos- 
phere through which heat rays pass with difficulty. 
Transpiration is also lessened in many of the grasses by the 
well-known phenomenon of the conduplication and inrolling 
of the leaves. In such grasses the stomata are almost always 
upon the upper side of the leaf. In others evaporation is hin- 
dered by the possession of thick cuticles, strongly impreg- 
nated with suberin, and in the case of Agropyrum and other 
§tasses by the thickening of the walls of the cells composing 
the fibro-vascular sheath. The increased transpiration which 
results from shocks is hindered in the dune plants by their 
remarkable rigidity, which is due both to the rolling up of 
the leaves and the extraordinary development of sclerenchy- 
matous tissue. The plants of the schorres owe their rigidity 
to their fleshy nature. 
Injury from excessive light is prevented in some cases by 
the hairs situated upon the upper surface of the leaves, shad- 
ing the green cells, thus hindering chlorovaporisation. In 
the genus Halimus the edges of the leaves turn towards the 
sun to secure the same object. 
3. Protection against the wind and animals. The high 
Winds exercise a very destructive influence upon the littoral 
flora, not only by breaking stems, tearing leaves and denud- 
ing the roots, but also by their great drying action. To ob- 
viate this the majority of the arenicolous plants are tough and 
elastic; others have strong hold-fast roots or a compact and 
Prostrate habit; still others produce numerous stolons. 
_Protection against animals of the littoral, of which the rab- 
bit is chief, is afforded to some plants by their hard character 
and impregnation with silica; some (Hippophaé, Eryngium) 
