22 Society for Experimental Biology and Medicine. 



crackers and milk, which furnished 0.0057 gram iron and 2.65 

 grams calcium oxide (Exp. I), there was equilibrium with respect 

 to iron, and a storage of calcium. When the diet consisted of 

 crackers and egg-white with 0.0065 gram iron and o. 14 gram lime 

 (Exp. II), or of crackers alone with 0.0071 gram iron and 0.13 

 gram lime (Exp. Ill), there were losses of both iron and calcium. 

 These losses occurred through 'the intestine, but were evidently 

 not due to intestinal putrefaction, since the ratio of sulphur in 

 ethereal to that in simple sulphates in the urine was determined in 

 Exp. Ill and found to be as 1 : 25. The results appear to con- 

 firm the suggestion of Von Wendt that a deficiency of calcium in 

 the diet may lead to a loss of iron as well as of calcium from the 

 body. There was a slight tendency toward diarrhea in each of 

 the periods in which loss of iron and calcium occurred. The iron 

 requirement evidently varied greatly, the average daily output for 

 three experiments being 5.5, 8.7 and 12.6 milligrams respectively. 



The lime requirement was found by further experiments (IV 

 and V) to be about 0.75 gram of calcium oxide per day. 



The experiments were conducted at Columbia University in 

 cooperation with the U. S. Department of Agriculture and will be 

 described in detail in a bulletin of the Office of Experiment Stations 

 of that department. 



19 (162) 



The cause of the treppe. 



By FREDERIC S. LEE. 



\From the Physiological Laboratory of Columbia University, at the 

 College of Physicians and Surgeons.'] 



The treppe is usually ascribed to increased irritability caused 

 by activity. The cause of the increased irritability has remained 

 obscure. In studying the depressing action on muscle of its 

 fatigue substances the author often observed augmentation of 

 activity instead of depression. A more careful investigation of this 

 phenomenon shows that it may be produced by all of the three 

 recognized fatigue substances — namely, carbon dioxide, mono- 

 potassium phosphate, and paralactic acid. When a muscle is irri- 

 gated with an indifferent fluid containing one of these substances in 



