Page:Popular Science Monthly Volume 32.djvu/93

From Wikisource
Jump to: navigation, search
This page has been proofread, but needs to be validated.

haps be permissible to cite a few of the statistics. I give more details than would perhaps be appropriate in these pages, were it not for the novelty of the results, and the importance of their bearing upon the physiology of absorption of nutritive material in our bodies as well as upon the nutritive value of the oysters.

The changes in the constituents of the body ("flesh") were mainly such as would be caused by osmose, though there were indications of secretion of nitrogenous matters and, especially, of fats, which are not so easily explained by osmose. This I will speak of later.

The amounts of gain and loss of constituents which the bodies of the oysters experienced may be estimated either by comparing the percentages found by analysis before and after dialysis, or by comparing the absolute weight of a given quantity of flesh and the weights of each of its ingredients before, with the weights of the same flesh and of its ingredients after, dialysis. For the estimate by the first method we have simply to compare the results of the analyses of the floated and the not-floated specimens. Taking the averages of the two experiments, it appears that—

 The percentages of— Before dialysis. After dialysis
Water rose from 77∙9 to 82∙4
Water-free substance fell form 22∙1 " 17∙6
—— ——
 Total flesh 100∙0 100·0
Protein fell from 10∙5 to 3∙9
Fat fell from 2∙5 " 1∙9
Carbohydrates, etc., fell from 6∙9 " 5∙2
Mineral salts fell from 2∙2 " 1∙6
—— ——
 Total water-free substance in flesh 22∙1 17∙6

There was, accordingly, a gain in the percentage of water and a loss in that of each of the ingredients of the water-free substance. This accords exactly with the supposition that during the floating the flesh gained water and lost salts and other ingredients.

It will be more to the point to note the absolute increase and decrease in amounts of flesh and its constituents—in other words, the absolute gain or loss of each in the floating. Estimates by this method have been made and explained in the detailed accounts referred to. They make it appear that 100 grammes of the flesh as it came from the salt water was increased by floating, in one specimen, to 120∙9, and in the other to 113∙4 grammes. This is equivalent to saying that the two specimens of flesh gained in the floating, respectively, 209 and 13∙4 percent, or, on the average, 17∙3 per cent of their original weight. By the same estimates the water-free substance in the 100 grammes of flesh before the floating weighed, on the average, 22∙1 grammes, while that of the same flesh after floating weighed only 20∙6 grammes, making a loss of 1∙5 gramme or 6∙6 per cent of the 22∙1 grammes which the water-free substance weighed before dialysis. The main