STRUCTURE. 



75 



while the tuberous species in like circumstances lose all of their foliage 

 and form tubers, from which they come out again first with water-leaves. 



FIG. 34. First leaves frnm germinating tubers: 1, first, 2, second submerged leaf; 3, first, 4, third 

 floating leaf of N. giyantea ; 5, second floating, 6, first, 7, second submerged leaf of IV. flavo-rirens ; V, first, 

 9, second, 10, third submerged leaf of N. caerulea ; 11, 12, first submerged leaf from brood body of 

 N. mexicana and N. flava, respectively ; 13, second floating, 14, second, 15, first submerged leaf of 

 N. eleyans ; 16, first, 17, second, 18, third submerged. 19, first floating leaf of N. zanzlbariensia rosea ; '20, 21, 

 first and second submerged leaves of N. "Mrs. C. W. Ward" (N. flavo-vircns X zanzibariensis). All 

 natural size. 



Wachter's (1897) observations on N'.stel/afa, dcntata, ntbra, thermalis, 

 and alba showed, by cutting off the roots or leaves from growing plants, 

 that production of water-leaves could be induced by enfeebled nutrition, 



