Special Functions and Relations 177 



Other investigators regard calcium as important, in 

 the main, in the neutralization of oxalic acid and acid 

 oxalates, assumed to be a factor in protein synthesis. 

 Neutralization is often effected in this way, for calcium 

 oxalate is of frequent occurrence; yet in some of the 

 higher plants there is no such accumulation of oxalates. 



Boehm considered calcium essential in the formation of 

 the cell- wall, and while he erroneously interpreted this 

 to be similar to the use of calcium in bone formation, yet 

 the relation of an adequate calcium supply to the forma- 

 tion of cell-walls has been clearly brought out by many 

 investigators. This apparent function may be merely an 

 indication of imperfect use of carbohydrates as above 

 discussed. Moreover, the formation of complete cell- 

 walls in the various fungi without calcium is against any 

 supposition of its direct importance in modified cellulose 

 formation. 



As early as 1880 it was ascertained that salts of magne- 

 sium are toxic when used alone, and that this toxicity dis- 

 appears when sufficient calcium is present in the nutrient 

 solution. In recent times the peculiar and antagonistic 

 relation which exists between calcium and magnesium, and 

 also between other nutrient elements to a less extent, has 

 been more completely developed. The work begun by 

 Von Raumer, and followed up by Loew, Loeb, Kearney, 

 and Osterhout, will be discussed at greater length under 

 Balanced Solutions. It is necessary, at this time, merely 

 to indicate that calcium is important in preventing the 

 injurious effects of an excess of magnesium. 



Calcium in protein formation. In studying this rela- 

 tion of the elements, Loew has developed an important 



