82 THE POPULAR SCIENCE MONTHLY. 



whole boat-load. The remainder were taken to the brackish water of 

 a stream emptying into the bay and kept upon the floats for forty- 

 eight hours, this being the usual practice in the floating of oysters in 

 this region. At the end of that time, the oysters were taken from the 

 floats, and a number fairly representing the whole were selected as 

 before. Two lots, one floated and the other not floated, were thus 

 taken from each of two different beds. The four lots were brought 

 to our laboratory for analysis. 



The specimens as received at the laboi*atory were weighed. There- 

 upon, the shell-contents were taken out, and the shells and shell-con- 

 tents both weighed. The solid and liquid portions of the shell-contents 

 — i. e., the flesh or " solids " and liquor or " liquids " — were weighed 

 separately, and then analyzed. We thus had, for each lot, the weights 

 of flesh and liquids which, together made the weight of the total shell- 

 contents, and the weight of the shells, which with that of the shell- 

 contents made the weight of the whole specimens. We also had, 

 from the analyses, the percentages of water, nutritive ingredients, 

 salts, etc., in the flesh and in the liquids. From these data the calcu- 

 lations were made of the changes which took place in floating. For 

 the details, which are somewhat extended, I may refer to the publica- 

 tion mentioned above. It will suffice here to give only the main re- 

 sults. It is assumed that the changes in the composition of the body 

 of the animal, due to respiration, nutrition, excretion, etc., during the 

 floating would be too small to be taken into account. 



The body of the animal may be regarded as made up of water and 

 so-called w ater-free substance. The water-free substance contains the 

 nutritive ingredients or "nutrients." These may be divided into four 

 classes: 1. Protein compounds, the so-called " flesh-formers," which 

 contain nitrogen* ; 2. Fatty substances, classed as fats ; 3. Carbohy- 

 drates ; 4. Mineral salts. These constituents of the flesh of oysters 

 have been but little studied. It is customary to assume them to be 

 similar to the corresponding compounds of other food-materials, but 

 very probably the difference, if known, might prove to be important. 

 The mineral matters especially, which are very large in amount, appear 

 to include considerable of the salts of sea-water. Of the nature of the 

 ingredients of the liquids but little is known. They consist mainly 

 of water and salts and the amounts of their ingredients which are 

 commonly reckoned as protein, fats, and carbohydrates, are very small, 

 so that whatever error there may be in classing them with the ordinary 

 nutrients of food, it will not very seriously affect the estimates of nu- 

 tritive values. 



During the sojourn in brackish water, both the flesh (body) and 

 the liquid portion of the shell-contents of the oysters suffered more or 

 less alterations in composition. In order to show clearly what the 

 principal changes, as shown by the chemical analyses, were, it may per- 



* The protein is estimated in the usual way by multiplying the nitrogen by 6"25. 



