402 



SCIENCE 



[N. S. Vol. XXXVII. No. 950 



copper in this way, but in the more recent 

 studies the results seemed to point to the 

 practical harmlessness of the metal in 

 green peas and beans. In consequence of 

 these French investigations, and later ones 

 in Germany, the use of copper in limited 

 amounts is now tolerated by the food laws 

 of most European countries. 



There seems to be no question regarding 

 the physiological action of relatively large 

 amounts of copper salts. They behave as 

 irritant poisons and produce nausea, vomit- 

 ing, purgation, while the small quantities 

 absorbed exhibit characteristic lesions in 

 the liver, spleen, kidneys and other organs. 

 We are concerned, however, with amounts 

 far below those necessary to cause any such 

 violent symptoms, amoimts which could 

 scarcely exceed 15 to 20 milligrams of cop- 

 per daily in any case, and usually much 

 below this. In the coloring of peas and 

 beans the amount of sulphate used is gen- 

 erally less than 1 gram per kilo, a part 

 only of which becomes fixed in the product, 

 the actual copper content being from 25 to 

 150 mg. per kilo, ordinarily. 



What are the effects of small doses, up 

 to 20 milligrams of copper daily? To 

 answer this question experiments have 

 usually been made with the sulphate or 

 other soluble salt, but it should be recog- 

 nized that this does not exactly correspond 

 to the practical situation, since in the pea 

 or bean the copper is largely combined as 

 phyllocyanin compound, which in its solu- 

 bility is very different from the ordinary 

 salts, and is much more stable. 



The results of a long series of experi- 

 ments carried out in my laboratory in the 

 last two years have convinced me that the 

 copper perfectly combined in this chloro- 

 phyll derivative is practically without any 

 evident physiological action in amounts 

 up to 12 or 15 milligrams daily, which 



amounts would be contained in a weight 

 of the vegetable as large as any one could 

 eat with a relish for more than a short 

 period. There appears to be no effect on 

 body weight, nitrogen metabolism, blood 

 factors or qualitative or microscopic blood 

 findings. Nausea is not produced. But 

 the case is somewhat different when we 

 turn to small doses of copper salts given 

 in tea, coffee, milk or beer. Here in time 

 we notice some effect, especially in causing 

 nausea and digestive disturbances, and also 

 in some cases a slight modification of the 

 nitrogen partition and some of the blood 

 factors. 



In young vegetables with high chloro- 

 phyll content the copper sulphate used in 

 small amount appears to be very perfectly 

 combined. This compound is remarkably 

 stable and resists the action of the digestive 

 ferments to a degree which prevents any 

 great absorption of the copper. In the 

 case of the green pea especially the chloro- 

 phyll is largely in the hulls, and these, 

 still green with their copper compound, 

 may pass through the alimentary tract and 

 be found in the feces but little changed. 

 This copper-chlorophyll complex is but 

 slowly broken up by hydrogen sulphide 

 or ammonium sulphide. 



In older vegetables, however, where the 

 chlorophyll has become considerably de- 

 sti'oyed this copper compound can not be 

 formed to the same extent and the copper 

 added in the canning operation goes into 

 a union with proteins which is easily 

 broken down. In this case the copper acts 

 much as it does in the ordinary inorganic 

 salts. In experiments I have found it pos- 

 sible to add 250 to 300 milligrams of cop- 

 per per kilo to old green peas, and others 

 have reported still higher additions. Much 

 of this copper may be separated easily by 

 dilute hydrochloric acid. 



