SOME NOTES ON THE VICTORIA REGIA. 221 



diameter, and is placed in about six tons of prepared soil in the 

 basin of the tank, which is about eight feet by two feet six 

 inches deep. The tank itself is about twenty-eight feet in 

 diameter, containing water kept at a temperature as near 85"^ 

 as possible. The plant soon becomes- established, covering 

 the surface of the water with its handsome leaves. As a 

 rule, only one flower expands at a time. The first leaf pro- 

 duced is very remarkable, including the stalk, which is scarcely 

 distinguishable from it, is about two inches long and devoid 

 of spines ; the second rather longer, and in it the leaf and 

 stalk are differentiated, and two or three spines appear on the 

 stalk ; the third is somewhat larger and rather similar in 

 shape, with more spines on the stalk ; the fourth assumes 

 an oval form with pointed ends, the one over the stalk with 

 a deep notch in it ; spines begin to develop on the chief 

 nerve. The colour underneath is of a reddish hue, and the upper 

 surface is marked with chocolate-coloured blotches. The stalk 

 lengthens and is covered with small spines. These spines have 

 ■spiral vessels and a small cavity in their interior, opening by a 

 little pore at the top. From the under surface of the base of the 

 leaf-stalks numerous adventitious roots are given out. The leaf- 

 stalks, flower-stalks, and nerves are traversed by numerous air- 

 channels, which make the enormous leaves so well adapted to float 

 on the water, when we remember the size and number of the veins. 

 In the leaves of submerged water-plants, however, the strands are 

 insignificant and many are even destitute of vessels, which is easily 

 understood, as the need of resisting pressure and bending in sub- 

 merged leaves is very slight. In most flat membranous leaves, 

 which have one side directed towards the sky and one towards the 

 earth, stomata are entirely wanting on the upper surface, being 

 restricted to the under side. An exception to this is afforded by 

 the leaves of the Victoria Regia and some others, they being 

 covered with stomata on the upper side, while on the lower side, 

 which is in contact with the water, stomata are entirely absent. 

 It may be observed that the water-lilies have small stomata, and 

 land ones, which belong to another order ( Liliacecz),. have large 

 ones. The whole of the upper surface can receive the rays of the 

 sun, and is thus warmed and illuminated throughout. The under- 



