B. P. I.— 61. V. P. P. I.— 702. 



THE PHYSIOLOGICAL ROLE OF MINERAL 

 NUTRIENTS IN PLANTS. 



GENERAL REMARKS ON THE MINERAL CONSTITUENTS FOUND 



IN ORGANISMS. 



HISTORICAL NOTES. 



The functions of the mineral nutrients in plants and animals consti- 

 tute a highly important problem. Normal development is impeded by 

 the decrease and entirely prevented by tho absence of even a single 

 nutrient, and gradual decline, disease, and finally death will result 

 from the continued withholding of any such substance. Thus yellow 

 spots will develop on the leaves of the sugar beet when the soil is defi- 

 cient in lime; mold fungi will not develop spore- but only mycelium 

 when the amount of magnesia in the nourishing medium becomes too 

 .small; and even the primary segmentation will stop entirely in the 

 fecundated eggs of lower marine animals when lime salts are withheld, 

 while every further physiological action comes to an end as soon as 

 sodium salts are substituted for potassium salts in the cells. Pigeons 

 die in a few weeks when fed with materials too poor in mineral matter, 

 and dogs can not subsist on meat which has been macerated with cold 

 water, by which means most of the mineral matter is removed. The 

 result of eating such food is weakness of the muscles and nervous 

 excitability, which finally lead to death with spasms and the symptoms 

 of suffocation. 



In examining highly differentiated plants and animals there are 

 ol "served not only certain differences as to the total sum of mineral 

 matter in the different organs of the same organism, but also certain 

 regularities as to the proportions of the mineral constituents. On the 

 other hand, pathological conditions lead to a partial excretion of the 

 mineral matter. Thus, in tuberculosis of man the excretion of lime 

 and magnesia is increased, and in diabetes the increased excretion of 

 lime is a specific symptom. These facts can be understood properly 

 only when it is admitted that for the normal functions of organs a 

 certain amount of lime and magnesia is indispensable. 



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