39^ 



RECREATION. 



not seem probable that the oysters would 

 secure ^od enough to make an appreciable 

 gain in weight in the short time in which 

 they remain in the fresh or brackish water. 



It is known that when a solution of salts 

 is separated by a suitable membrane from 

 water containing a lesser quantity of salts 

 in solution the passage of salts immediately 

 begins from the concentrated to the dilute 

 solution. This is practically the condition 

 which exists when the oyster is transferred 

 from salt to fresh or brackish water. The 

 fleshy portions of the body, which are en- 

 closed in a membrane, contain salt in solu- 

 tion. As long as the oyster stays in salt 

 water the solution of salts within its body 

 would naturally be in equilibrium with the 

 water outside. When the oyster is brought 

 into fresh or brackish water, i. e., into a 

 more dilute solution, at might be expected 

 that the salts in the more concentrated so- 

 lution within the body would pass out and 

 a larger quantity of fresh water would 

 enter and would produce such a dis- 

 tention as would actually take place dur- 

 ing floating. Careful experiments have 

 shown that this supposition is correct ; that 

 is, the oysters actually gain in weight. This 

 is due largely to the fact that they lose 

 mineral matter and gain a considerable 

 quantity of water. At the same time there 

 is a slight loss of nutrients. When in 

 their natural condition oysters contain 1-8 

 to 1-5 more nutritive material than iwhen 

 fattened. In the opinion of many consumers 

 the improvement in appearance and flavor 

 due to the removal of the salts more than 

 compensates for the loss in nutritive value. 

 It seems also to be a matter of common 

 opinion that oysters keep better when part 

 of the salts has been removed by floating. 

 However, experience of the New Jersey 

 Experiment Stations has shown that fresh- 

 ened oysters will not remain alive so long 

 as those taken directly from salt water. 

 Freshening increases rapidly the rate of 

 weakening and decay, the life period being 

 reduced one-half. 



Frequently oysters become more or less 

 green in color. There is a widespread opin- 

 ion that greening is injurious. The color 

 has been attributed to disease, to parasites, 

 and to the present of copper. It is in reality 

 frequently due to the fact that the oysters 

 have fed on green plants of simple struct- 

 ure, which are sometimes found in abund- 

 ance in brackish or salt water. The green 

 coloring matter of the plants is soluble in 

 the oyster juices and colors the tissues. The 

 opinion of those who have investigated the 

 matter carefully is that such green color is 

 harmless. In Europe green oysters are more 

 highly prized than others. The green color 

 may be removed by placing the oysters for 

 a time in water where the green plants are 

 not abundant. 



EARLY EXPERIMENTS ON THE DIGESTI- 

 BILITY OF EGGS. 



Raw eggs, or eggs only slightly cooked, 

 are said to be easily digestible, the idea be- 

 ing that they digest readily without giving 

 rise to pain or other physical discomfort. 

 The term digestibility has another meaning, 

 and one which is commonly intended when 

 it is used in the discussion of food values. 

 This refers to the thoroughness of diges- 

 tion; that is, to the total amount of mate- 

 rial which any food gives up to the body 

 in its passage through the digestive tract. 

 Since only soluble or possibly emulsified 

 matter can pass through the walls of the 

 stomach and intestines and be taken up 

 into the circulation to nourish the body, it 

 follows that only material which is soluble 

 or rendered soluble by the action of pepsin, 

 trypsin, and other ferments in the diges- 

 tive juices, is truly digestible. The origi- 

 nal condition of food, the method of cook- 

 ing, and the amount eaten at a given time, 

 are among the factors which determine the 

 quantity of any given material which can 

 be digested. 



Statements are frequently made with re- 

 gard to the length of time required to di- 

 gest different foods. Many of these are 

 doubtless far from accurate, as the subject 

 is not easy to study. By methods of arti- 

 ficial digestion, the length of time required 

 to render different foods soluble has been 

 frequently tested. It is possible to use in 

 the experiments the same digestive fer- 

 ments which occur in the body and to ap- 

 proximate body temperature, etc., but 

 not all the conditions of digestibility in the 

 body can be reproduced in the laboratory. 

 The results obtained are interesting and 

 often valuable, but it is worthy of note that 

 careful investigators are much slower to 

 make sweeping deductions from them than 

 are popular writers on the subject. Some 

 years ago Dr. Beaumont, a United States 

 army surgeon, had an excellent opportu- 

 nity for studying digestibility in the 

 stomach. A healthy young man was acci- 

 dentally wounded in the stomach by the 

 discharge of a musket. In time the large 

 wound inflicted healed, leaving a perma- 

 nent opening into the stomach. This was 

 ordinarily closed by a valvular flap made 

 by a fold of the stomach lining, which 

 could be easily pushed aside and the inte- 

 rior of the stomach examined or the con- 

 tents removed, as desired. Strange as it 

 may seem, this could be done without giv- 

 ing the subject pain or annoyance, nor was 

 his general health abnormal after the 

 wound had healed in this curious way. 

 For many years after the time of the acci- 

 dent (1822), the man was under Dr. Beau- 

 mont's care and observation. Many ex- 

 periments were made on the length of time 

 required by different foods for digestion in 

 the stomach, or chymification. Many arti- 



