10 



THE GARDEXER. 



plants properly belong to a moist climate. Plants 

 whose leaves have an intermediate structure, will 

 answer for positions in which nourishment is derived 

 from the earth and air in intermediate degrees. 



But more however, the Professor continues to ob- 

 serve, depends upon the relative size of the stomates 

 than on their number in researches of this kind ; these 

 organs, though in many plants very numerous, are so 

 small as to appear incapable of more than very limited 

 action ; while in others in which they are fewer, they 

 are large, and endowed with activity. He gives re- 

 markable illustrations of this. On a square inch of 

 the Crinum amabile there are about forty thousand 

 stomates, forty-five thousand on an equal surface cf 

 the Aloe, and seventy thousand in the Mesen.brycn- 

 themum. The first of these is a native of the bun: id 

 parts of India, and the two others grow on the arid 

 rocks of the Cape of Good Hope ; but the stomates of 

 the Crinum amabile are amongst the largest of those 

 in any known plants ; in the other two the st:n::-.:es 

 are amongst the smallest that h^ve been ol-ewed; 

 and it is computed that the seventy thcn-r.n:'. s::n:a:es 

 of the Mesembryanthemum are nor equal m power to 

 ten thousand of the Crinum. Thus also the Yucca 

 aloi'folia has four times as many of these parts as a 

 particular variety of the Cotyledon ; but in the latter 

 they are l-750th of an inch in their lon_:est diame- 

 ter, and are large and active: while ihe^e o:' the Yucca 

 have only 1 -2500th of an inch at the greatest exten- 

 sion, and appear comparatively inefficient. The Yucca, 

 therefore, not with s : a.: a in g the vast number of pores in 

 its leaves, posse :?ses less evaporating power than the 

 Cotyledon. 



According to the same writer, the leaf performs 

 functions analogous to those which the lungs and 

 stomach discharge in animals ; it contains the veinous 

 system also, and performs an important part in elabo- 



