308 BOTANICAL GAZETTE [april 



9.86 per cent of ash with the following composition: CaO, 8.2 

 per cent; CI, 15.2 per cent; Na 2 0, 48.47 per cent; K 2 0, 0.86 

 per cent; P 2 O s , 14.36 per cent. The presence of sodium hydroxide 

 or of sodium carbonate in the water solution of this ash seems 

 probable. 



There seemed to be 5 possibilities as to the cause of the toxicity 

 of the products of the decay of this rhizome: (1) the presence of 

 the organisms; (2) toxicity due to ionization; (3) the presence of 

 toxic molecules; (4) high osmotic pressure of the solutions; and 

 (5) low surface tension of the solutions. Of these, (1) seems to 

 be practically eliminated by the work here reported. Apparently 

 the presence of organisms, either at the time of the formation of 

 the solution or at the time of their action on growing plants, is 

 not a condition necessary for their toxic action. Work elsewhere 

 reported (20) disposes of (4) and (5). This leaves ionization and 

 toxic molecules as probable causes of the toxicity. The relative 

 importance of these two is not fully determined by the work here 

 reported. It is evident, however, that the entire toxicity cannot 

 be ascribed to one substance. If we should suppose that the 

 toxicity of all of the solutions obtained from this rhizome was due 

 to only one substance, it would have to have the following prop- 

 erties: (1) soluble in water; (2) soluble in ether; (3) volatile at 

 40 C, 20 mm. pressure; (4) stable at 250 C, 15 lbs. pressure; 

 (5) absorbed by animal charcoal; and (6) precipitation by am- 

 monium sulphate. 



It seems probable that there are at least 3 classes of substances 

 here that are somewhat toxic: (1) colloids, (2) very volatile sub- 

 stances, and (3) certain bases. 



Summary 



1. The products of the decay of Nymphaea rhizomes are toxic 

 to Tradescantia cuttings, and to tomato, alfalfa, and corn, even in 

 very dilute solutions. 



2. All of the solutions prepared except the one from the ash 

 were acid, but the amount of acidity was not proportional to the 

 degree of toxicity. 



