402 ISIDOR GREENWALD 



but were probably not greatly different from those to which the men had 

 been accustomed. 



In 1890 von Rechenberg published the results of his studies of the 

 families of hand weavers in Zittau, a small town in Germany. The average 

 intake of protein was 1.14 grams per kilo, but the condition of the people 

 indicated that they were undernourished. They were very poor and their 

 diet was not at all what they would have selected had they enjoyed better 

 conditions. 



Neumann's Experiments. Neumann's studies on himself were really 

 the first to show that so low a level of protein metabolism could be obtained 

 on a mixed diet and maintained for a considerable period without evidence 

 of ill effect. The diets were such as he had been accustomed to, although 

 necessarily restricted in variety during the course of his studies, for he 

 analyzed many of the foods himself. The first experiment included 305 

 consecutive days. In the following year there was a second experiment of 

 120 days. Three years later (four years after the first) a third study was 

 begun. With the exception of November, December and January, this 

 extended from May 1900 to June 1901. While reported as one experiment 

 of 321 days, it really consisted of two separate studies of approximately 

 half that length. The protein intake in the first and third studies was 

 approximately one gram per kilo and, in spate of the rather low content 

 of energy, Neumann gained slightly in weight. There was no evidence of 

 any ill effect. 



In the second experiment referred to, all the foods used were analyzed 

 and the nitrogen of the urine and feces was also determined. Neumann 

 found that he lost nitrogen and weight on the food as he then selected it 

 and retained both only on a rather higher level of protein and energy in- 

 take than in the previous experiment. The values now obtained over a 

 suitable period of 15 days were 1.16 grams protein and 40 calories per 

 kilo per day. It seems probable that a consistent error was responsible for 

 the much lower values for energy content in the other, not carefully ana- 

 lyzed, diets. 



Chittenden's Experiments. Very soon after the appearance of Neu- 

 mann's paper, Chittenden published the results of his long-continued ob- 

 servations on himself, his friends and associates, on college athletes and on 

 a group of soldiers. The experiment on himself was begun when he was 

 47 years old and weighed 65 kilos. He gradually reduced his diet until, 

 eight months later, he weighed only 58 kilos. By that time an 

 arthritis had disappeared, not to return, and he no longer suffered from 

 headaches and bilious attacks which had formerly appeared periodically. 

 He was able to do as much physical work as formerly with less than 

 the customary degree of fatigue and muscular soreness. Observations 

 during the following year showed that the nitrogen of the urine averaged 

 5.69 grams per day and that the intake with the food was approximately 



