The muscular system generally lasts the shortest period, the nervous system the longest. The role of magnesium in organic synthesis leads one to think that it must diminish with age. Weiske's work shows that magnesium is less abundant in the bones of old rabbits than it is in those of young ones. In the human testicles a decline in magnesium was demonstrated as a person ages, but in old age calcium is more abundant than magnesium-three times more abundant. But here is something extremely interesting.
Calcium is static, magnesium is dynamic.
In the brain and in the testicle, the relationship with age of are the same degree, but it appears certain to us that at the time that life is waning, magnesium diminishes while calcium rises. Now, everything that is known about the chemical magnesium, about its action in the synthesis of chlorophyll, justifies one in thinking that its reduction plays a role in senility, or at least in certain phenomena of senility.