FOOD VALUE OF SEA MUSSELS. 
103 
The animal was catheterized immediately before feeding the day’s ration, and at three-hour intervals 
thereafter for twelve hours, then again at the end of twenty-four hours after feeding, the bladder being 
washed out with 0.6 per cent sodium chloride solution at each catheterization. The nitrogen excreted 
in the urine during each interval was determined by Kjeldahl analysis. The urine obtained at each 
catheterization, combined with the cage washings in case the dog had urinated during the interval, 
was acidified with sulphuric acid, diluted to 500 or 1,000 volumes, and one-twentieth taken for 
analysis. 
The feces containing the undigested portions of each day’s rations were collected and the nitrogen 
content determined. The animal charcoal in the alternate day’s feces made a separation possible, 
and the 5 grams of bone ash fed daily insured a well-formed, solid, stool. 
It was found that analysis of both food and feces for nitrogen and fat could be made accurately 
without preliminary drying in a dessicator. For fat analysis about 10 grams of the fresh material were 
ground up with anhydrous copper sulphate until the mixture became a dry, homogeneous powder. 
This was extracted for about ten hours with carbon tetrachloride, ground again, and reextracted for 
a few hours. Representative samples of flesh for nitrogen determination were obtained by grinding 
the flesh as fine as possible in a meat grinder, and taking 2 grams or more for the sample. 
The daily diet consisted of 25 grams of fat, 50 grams of cracker dust, and sufficient beef or fish flesh 
to bring the total nitrogen of the diet up to the amounts indicated in the table. About three-fourths 
of the protein ration was contained in the flesh, the other one-fourth in the cracker dust. To the lard, 
cracker dust, and meat were added 5 grams of sodium chloride and 5 grams of bone ash. 
After being fed squid for two days, the dog refused to consume completely the rations offered and 
was partially starved for several days. During the feeding of raw beef and squid she consumed and 
excreted 2.5 grams of nitrogen daily, as indicated in the two lower curves of the figure. 
The results are briefly indicated by the following tables and figure : 
Table 2. — Showing Results of Metabolism Experiments. 
Ration containing — 
Raw beef. 
Steamed 
squid. 
Steamed 
beef. 
Steamed 
mussel. 
2. 497 
■ 423 
2. 074 
83- 1 
2. SOS 
. 291 
2. 214 
88. 4 
2 . 085 
. 285 
1 . 800 
86.3 
2. 131 
• 444 
1 . 687 
79 - I 
Nitrogen digested 
Per cent nitrogen digested 
Ration containing — 
Raw beef. 
Steamed 
squid. 
Steamed 
beef. 
Steamed 
mussel. 
Nitrogen in ration (grams) 
Nitrogen in urine +feces 
Nitrogen retained 
2. 497 
2. 489 
+ 0. 01 
2 - 5°5 
2. 48s 
+ 0. 02 
2. 085 
1 . 910 
+ 0. 18 
2. 131 
2. 1 17 
+ 0. 01 
conclusion. 
The above results indicate (table 2) that the protein of the ration containing steamed mussel 
was digested somewhat less completely (79.1 per cent) than that of raw beef (83.1 per cent), while the 
squid gave higher results (88.4 per cent) than the raw beef. The steamed-beef figures (in table, not 
in the figure) are of doubtful accuracy, as a portion of the feces may have been lost, causing the high 
figures for digestibility (exceeding those of raw beef, which is improbable) and for nitrogen retention 
The digestibility figures indicate only the relative digestibility of the meats fed. A considerable 
