It is the magnetic iron in haemoglobin which makes every sort of nervous function possible, in the cerebral (brain) and in the sympathetic (intestinal) tracts, and since it is thus made clear that intellectual activity on the one hand and breathing and digestion and excretion on the other are dependent on the iron content of the blood, we must also recognize that, as iron attends every nerve action, the secretion of urine too takes place under the influence of haemoglobin.  Insofar as haemoglobin hastens the departure of the excrementitious matter in urine out of the system, there is a daily loss of iron in the urine.  This loss in the form of urohaematin may total four centigrams, or a hundredth part of our supply.

This loss of iron if not replaced by eating suitable food will soon make itself felt.  In the course of a day the reduction by four centigrams will diminish the energy of nervous activity about 1440 times the apparent loss, so that even a four weeks-tropical fever, during which no meat is eaten, may completely exhaust the strength of an individual.  Moreover, iron conditions bodily warmth as it combines with oxygen in a higher and a lower degree.  In the lungs it is highly oxidized by the respired oxygen, but in contact with the nerve ends it gives itself only to a part of the oxygen present, and burns a certain portion of the lecithin to water, carbonic acid and phosphates, thus creating body warmth to a considerable extent.

In response to the chemical consumption of lecithin a new oil flows down the axis cylinders of the nerve fibrils, which are arranged like lamp wicks.  The duration of the flow of this oil is, on the average, about eighteen hours.  When the cerebro-spinal nerves refuse longer to perform their function, fatigue and sleep ensue, and the current of blood leaves the brain and seeks the intestines.  While the cerebro-spinal system rests, the sympathetic system takes up its task of directing the renewal of tissue and supplying the nerve sheaths through the lymph vessels, which draw their material from the digestive canal, with a new supply of phosphatic oil.  Thus the brain and spinal nervous system are prepared for another day’s work.  For the fulfillment of these processes, the magnetic blood current forms the intermediary.

The presence of formic and acetic acid supplies the blood with fresh electricity to stimulate the nerves.  “Under normal conditions,” says Julius Hensel, “this function is assigned to the spleen.  This organ takes the part of a rejuvenating influence in the body in the manner of a relay station, and does so by virtue of an invisible but significant device.  In every other region of the body the hairlike terminals of the arteries which branch out from the heart merge directly in the tiny tubes (capillaries) of the veins, which lead back to the heart again:  in the spleen this is not the case.  Here rather the arteries end suddenly when they have diminished to a diameter of one one-hundred-and-fortieth of an