DAVm I. MACHT AND MARGUERITE B. LIVINGSTON 



577 



The minimal concentration required to inhibit growth completely 

 was 0.06 molar, or about 2 per cent. Solutions slightly more dilute 

 {e.g. 0.05 molar, or 1 per cent, allowed a growth increment of 64 

 per cent) , and still weaker solutions did not impair the growth at all. 

 In some of the experiments, indeed, as for instance in concentrations 

 of 0.0000005 molar and 0.0001 molar, there was even a suggestion of a 

 stimulation in growth. This was not, however, definitely estabHshed, 

 because of lack of cocaine. The significance of the toxic dose of 

 cocaine for the lupine as compared with that of the same drug for 

 animal tissues will be discussed below. 



Toxicity of Ecgonine and Benzoyl Ecgonine. — Cocaine on being 

 hydrolyzed readily yields the base ecgonine. Neither ecgonine nor 



TABLE II. 



Relation between Concentration of Ecgonine Hydrochloride and Growth of Lupine 



Roots. 



benzoyl ecgonine exhibit the characteristic pharmacological properties 

 of cocaine in animals. The effects of these compounds on the growth 

 of lupine are shown in Tables II and III. Table II gives the effects 

 of various concentrations of ecgonine hydrochloride, while Table 

 III exhibits the results of experiments with benzoyl ecgonine. It 

 will be noted that the minimal concentration of ecgonine hydro- 

 chloride which produced complete inhibition of growth was 0.0025 

 molar, or 0.055 per cent. Weaker dilutions ranging from 0.001 to 

 0.00005 molar, inclusive, permitted growth, though considerably re- 

 tarding it. In concentrations of 0.00001 molar no deleterious effect 

 on the growth of the roots was evident. It is thus seen that ecgonine 

 is more toxic to lupine roots than is cocaine itself. 



