68 THE MICROSCOPE. 



from one trunk to a similar relation in the other ; caudal mesal 

 fibres exchange in like manner. The chiasmus is about lo mm. in 

 length. 



THE URINARY PHOSPH.\TES. 



BV GEO. F. HEATH, M. D., 



PHOSPHORUS was discovered in the year 1669 by Brandt. It is 

 met with in nature only in the combined state, and is found in 

 the primitive and volcanic rocks, and by their disintegration slowly 

 passes into the soil. Here it is taken up by the myriad forms of 

 vegetable life, and deposited more particularly in the seeds, as in 

 the peas, beans, corn, wheat, etc., thus becoming the food of the 

 animal kingdom ; the phosphorus in the plant being transferred, and 

 going to build up the tissues of the animal. 



We can thus easily see how important a part phosphorus plays 

 as an element in our food, and how it exists as a necessary element 

 in the vegetable world and entering into nearly all the structures of 

 the higher forms of animal life contributes largely to the formation 

 of bone, is the essential or life part of the blood, brain, muscular 

 and nervous tissues of the animal, and is an important agent in the 

 nourishment and building up of the body. 



Phosphorus is found in both the feces and urine of man ; origi- 

 nally it was obtained almost exclusively from the urine of animals, 

 but now almost wholly from bone by calcination. 



The average man will excrete in his urine about five grammes 

 of phosphoric acid daily. In proportion one gramme of the earthy 

 to four grammes of the alkaline phosphates. This is the result of 

 the oxidation of the phosphorus of the albuminoid tissues within the 

 body, and the disintegration of the muscular and nervous tissues, 

 the amount varying in proportion to the mental and muscular activity 

 of the individual, usually when the excretion is much above this, the 

 waste is greater than the repair and debility follows as a natural 

 consequence. 



As before stated phosphorus exists in the mineral kingdom, 

 only in a combined state ; the same is true in its relation to the ani- 

 mal kingdom. 



