Dec. 15, 1924 
Composition of Diet, Blood , and Milk 
615 
In order to test this hypothesis, the 
free tryptophane and the total amino 
N of the blood have been followed 
simultaneously in Experiments IV, VI, 
and VIII. (See Tables VI, VIII, and 
X.) From the results of these experi¬ 
ments the following conclusions may 
be drawn: 
1. Under appropriate conditions very 
great changes may occur in the concen¬ 
tration of the free tryptophane in the 
blood while at the same time relatively 
little or no change occurs in the blood 
amino N. In Experiment IV the 
tryptophane in the blood on Novem¬ 
ber 14 was 1.46 mg. per 100 c. c., and 
on December 9 it was 0.63 mg., a 
difference of 57 per cent. The differ¬ 
ence in blood amino N between these 
dates was only 14 per cent. In Experi¬ 
ment VI the blood tryptophane in¬ 
creased from 0.63 to 1.2 mg., or 90 per 
cent, with no increase in blood amino 
N; and in Experiment VIII the blood 
tryptophane increased about 100 per 
cent between periods 1 and 3 with 
practicallv no change in blood amino 
N. 
2. These alterations in the composi¬ 
tion of the blood mixture of amino acids 
may , under certain conditions, continue 
for weeks. On the low-protein ration 
in period 3 of Experiment IV the blood 
tryptophane dropped from 1.46 mg. to 
1.04, 0.82, and 0.63 mg. in four con¬ 
secutive samples taken during a period 
of 25 days. This drop in blood trypto¬ 
phane was probably caused by a de¬ 
crease in the rate at which the tissues 
yielded tryptophane to the blood. 
3. These experiments show that 
changes occur in the composition of 
the blood mixture of amino acids (a) 
when the quantity of protein in the 
ration is reduced, (b) when the quality 
of the dietary protein is changed, and 
( c ) when the quantity of protein in the 
ration is increased. 
The rise in blood tryptophane be¬ 
tween periods 1 and 2 from 1.03 to 
1.46 mg. in Experiment IV, and from 
0.34 to 0*45 mg. in Experiment VIII, 
might well be expected even in view 
of the fact that the quantities of 
tryptophane in the protein of the 
rations were low in the first periods 
of both experiments and still lower in 
the second periods. An amino acid 
like valine, which is lower relatively 
in both muscle and corn proteins than 
in milk proteins and is absent from 
gelatin, might well determine the ex¬ 
tent of increase in negative N balance 
in changing from the rations of the 
first period to those of the second 
period, and thus might effect a rise 
in blood tryptophane. This explana¬ 
tion accords with that given above for 
the subsequent drop in blood trypto¬ 
phane in period 2 of Experiment IV. 
Table IX .—Experiment VII, cow 246. Change in quality of protein in ration; 
no change in quantity 
Period No. 
Date 
Milk (daily) 
Amino N ® 
Yield 
i 
Fat 
Nitrogen 
Blood 
(mg. per 
100 c. c.) 
Plasma 
(mg. per 
100 c. c.) 
1922 
Kg. 
Per cent 
Grams 
i 
! Per cent 
Grams 
1 
Septembei 4-8.... 
12. 59 
3.41 
420 
1 0.440 
54. 5 
1 
September 9_ 
12. 70 
3.67 
466 
| . 440 
56. 0 
3. 98 
1 
September 10-12_ 
11. 90 
3. 78 
454 
. 447 
53.6 
1 
September 13 b _ 
11. 79 
3.71 
436 
. 456 
53.8 
3. 66 
1.83 
2 
September 14_ 
12.11 
3. 86 
468 
.453 
54. 9 
2 
September 15_ 
11.93 
3. 63 
433 
I .438 
52. 3 
l 
2 
September 16_ 
11. 61 
3. 40 
395 
. 438 
50. 9 
2 
September 17.. 
11. 66 
2 
September 18_ 
11. 52 
3. 98 
459 1 
. 462 
53. 2 
2 
September 19_ 
11. 52 
4.04 
465 j 
.456 
52.5 
4. 37 
2. 43 
2 
September 20_ 
11. 52 
3. 83 
441 I 
. 451 
52. 0 
2 
September 21_ 
11. 48 
3. 86 
443 
. 435 
49. 9 
2 
September 22_ ... 
11. 39 
3. 82 
435 ; 
. 453 
51. 6 
2 
September 23_ 
11. 30 
4. 28 
483 ! 
. 459 
51. 8 
2 
September 24_ 
11. 48 
4. 06 
466 ! 
.471 
54. 0 
2 
September 25_ 
11.25 : 
3. 93 
442 i 
.473 
53. 2 
2. 08 
2 
September 26_ 
11. 20 
4.17 
467 j 
.497 
55. 6 
2 
September 27_ 
11.34 
2 
September 28_ _ 
10. 89 
3. 78 
412 ! 
. 502 
54. 6 
I 
“Average difference in duplicate amino-N determinations in blood 2.9 per cent, and in plasma 2.9 
per cent. 
b On Sept. 13, 0.45 kg. of grain was refused 
