768 FRANCIS H. McCRUDDEN 



enamel laid down is free from calcium (Erdheim(e), Toyofuku). If the 

 extirpated parathyroids are transplanted into the abdominal wall of the 

 same animal, layers of uncalcified dentin are laid down until the trans- 

 planted parathyroids begin to function in their new location, when normal 

 dentin is again laid down (Erdheim (<?)). 



The evidence connecting parathyroid tetany, with disturbance of the 

 calcium metabolism is discussed in another chapter of this work (see 

 Parathyroids). 



Oxalic acid or oxalates in the food give rise to a negative calciurn 

 balance and lead to osteomalacia. In 1881 the number of cases of 

 osteomalacia in cows who were eating large quantities of beet tops in a 

 certain part of Germany, led to an investigation which showed that the 

 beet tops contain an abundance of oxalic acid (Haubner). Experiments 

 showed that administration of oxalic acid, or oxalate in the food, leads to 

 a negative calcium balance in rabbits (Caspari, Luithlen), sheep (Zuntz 

 (6), von Nathanius), dogs (Caspari), and guinea pigs (Sarvonat and 

 Roulier) ; a decrease in the calcium content of the bones (Caspari, von 

 Nathanius, Zuntz (&)). The administration of sufficient calcium car- 

 bonate offsets the action of the oxalic acid or oxalate, so that there is 

 neither a negative calcium balance (Zuntz (6), von Nathanius), a loss of 

 calcium from the bones (Caspari), nor osteomalacia (Caspari). 



In this connection it is interesting to note that osteomalacia can be 

 induced in rabbits by the injection of lactose (Bonnamour, Badolle and 

 Escallon) or glucose (Parisot, Badolle, Robert and Parisot). The 

 osteomalacia resulting from glucose injection is accompanied by 

 oxaluria, and the severity of the disease is proportional, not to the 

 amount of glucose injected, but to the intensity of the oxaluria (Parisot). 



Calcium oxalate is an insoluble substance, which is formed wherever 

 calcium and oxalate come together in alkaline, neutral, or oven slightly 

 acid solution. It is, therefore, quite probable that oxalate precipitates, or 

 at any rate renders physiologically inactive, any calcium salts which the 

 oxalate meets in the body; and that the flux of calcium salts from the 

 bone is the result of an attempt to supply the resulting deficiency. An 

 indication in this direction is given by the experiments of Chiari and 

 Froelich(fr), who found that the administration of sodium oxalate over- 

 comes the inhibiting effect of vagus stimulation on the heart. In the 

 belief that this oxalate action might be due to the precipitation or inac- 

 tivation of the calcium in the tissues, these investigators administered 

 calcium salts intravenously and restored normal condition. Chiari (a) 

 demonstrated also that oxalates have a similar action on the calcium of 

 the cells of the gastro-intestinal tract ; the calcium is precipitated and 

 thereby inactivated, leaving a preponderance of sodium salts whose stim- 

 ulating effect causes increased peristalsis. 



Since I came across the literature connecting osteomalacia with oxalic 



