| 8 | 63.8 | 22.62 | 22.86 | -0.24 | | | | | +----------| | | | | | +6.15 | +--------+--------------+-------------+-----------+----------+ I have ventured to give these data in some detail, because of their exceeding great interest in several directions aside from the point under discussion. Confining our attention to the nitrogen exchange, it is to be observed that for a period of two weeks Sivén lived on less than 3 grams of nitrogen per day, and without any excessive intake of carbohydrate or fat. During this time, the body naturally was in a condition of minus balance as regards nitrogen, the output being considerably larger than the income. The total amount of nitrogen lost in the period, 31 grams, corresponds to a breaking down of 193 grams of tissue proteid, or over one-third of a pound. On increasing the income of nitrogen to 4 grams per day, the nitrogen loss still continued, though at a much lower rate; indeed, the body is seen to approach very closely to a condition of nitrogen equilibrium. Still further increase of the nitrogen income to 13 grams per day was followed at once by a slight accumulation of proteid, and the body showed a decided plus balance of nitrogen, as on November 27. This, however, is seen to decrease gradually with a corresponding daily increase in the outgo of nitrogen, until on December 2 the body was once more practically in nitrogenous equilibrium. On again increasing the nitrogen income, to 23 grams per day, the same process was repeated, although in this case the body more quickly approached a condition of nitrogen balance. We see in these data striking confirmation of the statement that the nitrogen outgo tends to keep pace with the income of nitrogen, the body always striving to maintain a condition of nitrogen equilibrium. Consequently, the fasting man having lost largely of his store of proteid can replace the latter only slowly, even though he eats abundantly of proteid food. Thus, Sivén in the week ending December 2, though taking over 13 grams of nitrogen a day, retained in his body only 14.5 grams of nitrogen during the entire seven days; while in the six days following, with a daily intake of 23 grams of nitrogen, he gained only about 8 grams additional. The human body does not readily store up proteid, and this is true no matter how greatly the tissues are in need of replenishment.