144 MISSOURI BOTANICAL GARDEN. 



cation of various salts, which shows itself in the development 

 of giant cells, or in a state of excessive tumescence. The 

 salts of copper and ammonia must be regarded as exerting 

 a poisonous effect, that is they produce a functional de- 

 rangement in the organism which sooner or later results in 

 death of the affected parts. The action of poison in accel- 

 erating growth has been frequently noted, as for instance 

 in the case of chloroform or ether which may start 

 into growth, or accelerate growth of, resting organs. 

 "Poisons," says Pfeffer 18 , " like all other chemical in- 

 fluences, cause not only a retardation but also accelerate 

 either temporarily or permanently, the sum total of the 

 activities or special functions. 



In the case of the leaves of the cauliflower sprayed with 

 copper and ammonium salts, a very definite reaction took 



y > 



place which showed itself soon after the application of the 

 sprays in the very much increased turgidity of the spongy 

 parenchyma underlying the sprayed spots. This increased 

 turgidity may have been due to one of two causes. A re- 

 action may have taken place between the stimulating salt 

 and certain elements of the protoplast, resulting in the 

 formation of compounds within the protoplast having enor- 

 mously higtuosniotic coefficients. In order to have a poi- 

 sonous effect, as indicated by Pfeffer, most poisons must 

 be not only actively in contact with the protoplasts, but 

 they must actually enter into contact with the same. " The 

 action of the poisonous heavy metals is probably due to 

 their union with bodies which form parts of developing 

 proteid substances" (Pfeffer 23 ). It is easily conceiva- 

 ble that the copper salts might have penetrated into the 

 leaf tissue, resulting in the formation of a compound as sug- 

 gested. The second explanation is that possibly the va- 

 rious salts exerted some stimulating influence on the pro- 

 toplasts, of a character not understood, which resulted in a 

 reaction causing the production of a large amount of organic 

 acids, which would explain the increased turgidity of the 



