Part 19 (1/2)
Observation shows, that disease, habit, the state of the mind, and other circ.u.mstances, exert an influence on the appet.i.te.
284. Show the effect of habit upon the quant.i.ty of food that is eaten.
What is said in regard to inordinate eating? 285. What is the effect of eating large quant.i.ties of food? What suggestion when an extraordinary effort, either mental or physical, is to be made? 286.
How much food should generally be eaten? 287. What is the a.s.sertion of some persons relative to the quant.i.ty of food necessary for the system?
_Observation._ Dr. Beaumont noticed, in the experiments upon Alexis St. Martin, that after a certain amount of food was converted into chyme, the gastric juice ceased to ooze from the coats of the stomach.
Consequently, it has been inferred by some writers on physiology, that the glands which supply the gastric fluid, by a species of instinctive intelligence, would only secrete enough fluid to convert into chyme the aliment needed to supply the real wants of the system. What are the reasons for this inference? There is no evidence that the gastric glands possess instinctive intelligence, and can there be a reason adduced, why they may not be stimulated to extra functional action as well as other organs, and why they may not also be influenced by habit?
288. While all agree that the remote or predisposing cause of hunger is, usually, a demand of the system for nutrient material, the proximate or immediate cause of the sensation of hunger is not clearly understood. Some physiologists suppose that it is produced by an engorged condition of the glands of the stomach which supply the gastric juice; while others maintain that it depends on a peculiar condition of the nervous system.
289. The QUALITY of the food best adapted to the wants of the system is modified by many circ.u.mstances. There are many varieties of food, and these are much modified by the different methods of preparation.
The same kind of food is not equally well adapted to different individuals, or to the same individual in all conditions; as vocation, health, exposure, habits of life, season, climate, &c., influence the condition of the system.
What does observation show? 288. What is said of the causes of hunger? 289. Why is not the same kind of food adapted to different individuals?
290. All articles of food may be considered in two relations: 1st, As nutritive. 2d, As digestible. Substances are nutritious in proportion to their capacity to yield the elements of chyle, of which carbon, oxygen, hydrogen, and nitrogen are the most essential; they are digestible in proportion to the facility with which they are acted upon by the gastric juice. These properties should not be confounded in the various articles used for food.
291. As a ”living body has no power of forming elements, or of converting one elementary substance into another, it therefore follows that the elements of which the body of an animal is composed must be in the food.” (Chap. III.) Of the essential const.i.tuents of the human body, carbon, hydrogen, oxygen, and nitrogen are the most important, because they compose the princ.i.p.al part of the animal body; while the other elements are found in very small proportions, and many of them only in a few organs of the system. (Appendix G.)
_Observation._ Nitrogen renders food more stimulating, particularly if combined with a large quant.i.ty of carbon, as beef. Those articles that contain the greatest amount of the const.i.tuent elements of the system are most nutritious. As milk and eggs contain all the essential elements of the human system, so they are adapted to almost universal use, and are highly nutritious.
290. In what proportion are substances nutritious? Digestible? Why does beef stimulate the system? What is said of milk and eggs?
292. The following table, by Pereira, in his treatise on Food and Diet may aid the student in approximating to correct conclusions of the quant.i.ty of nutriment in different kinds of food, and its adaptation to the wants of the system.
TABLE,
SHOWING THE AVERAGE QUANt.i.tY OF DRY, OR SOLID MATTER, CARBON, NITROGEN, AND MOISTURE, IN DIFFERENT ARTICLES OF DIET.
-------------------+---------+---------+-----------+------------ One hundred Parts.
Dry
Carbon.
Nitrogen.
Water
Matter.
-------------------+---------+---------+-----------+------------ Arrowroot,
81.8
36.4
18.2 Beans,
85.89
38.24
14.11 Beef, fresh,
25
12.957
3.752
75 Bread, rye,
67.79
30.674
32.21 b.u.t.ter,
100
65.6
Cabbage,
7.7
0.28
92.3 Carrot,
12.4
0.30
87.6 Cherries,
25.15
74.85 Chickens,
22.7
77.3 Codfish,
20
80 Cuc.u.mbers,
2.86
97.14 Eggs, whites,
20
80 ----, yolk,
46.23
53.77 Lard, hog's,
100
79.098
Milk, cow's,
12.98
87.02 Oats,
79.2
40.154
1.742
20.8 Oatmeal,
93.4
6.6 Olive-oil,
100
77.50
Oysters,
12.6
87.4 Peaches,
19.76
80.24 Pears,
16.12
83.88 Peas,
84
35.743
16 Plums, greengage,
28.90
71.10 Potatoes,
24.1
10.604
0.3615
75.9 Rye,
83.4
38.530
1.417
16.6 Suet, mutton,
100
78.996
Starch, potato,
82
36.44
18 ----, wheat,
85.2
37.5
14.8 Sugar, maple,
42.1
----, refined,
42.5
----, brown,
40.88
Turnips,
7.5
3.2175
0.1275
92.5 Veal, roasted,
52.52
14.70
Wheat,
85.5
39.415
1.966
14.5 -------------------+---------+---------+-----------+------------
_Note._ Let the pupil mention those articles of food that are most nutritious, from a review of this table, and the last four paragraphs.
293. Those articles that do not contain the essential elements of the system should not be used as exclusive articles of diet. This principle has been, and may be ill.u.s.trated by experiment. Feed a dog with pure sugar, or olive-oil, (articles that contain no nitrogen,) for several weeks, and the evil effects of non-nitrogenous nutriment will be manifested. At first, the dog will take his food with avidity, and seem to thrive upon it; soon this desire for food will diminish, his body emaciate, his eye become ulcerated, and in a few weeks he will die; but mix bran or sawdust with the sugar or oil, and the health and vigor of the animal will be maintained for months. A similar phenomenon will be manifested, if grain only be given to a horse, without hay, straw, or material of like character. (Appendix H.)
294. Some articles of food contain the elements of chyle in great abundance, yet afford but little nutriment, because they are difficult of digestion; while other articles contain but a small quant.i.ty of these elements, and afford more nourishment, because they are more easily affected by the digestive process.
293. How has the effect of non-nitrogenous nutriment been ill.u.s.trated?
294. Why do some articles of food that contain the elements of chyle afford but little nutriment? Why do articles that contain a small quant.i.ty of these elements afford more nourishment? 295. How was the time required for digesting different articles of food ascertained?
295. The following table exhibits the general results of experiments made on Alexis St. Martin, by Dr. Beaumont, when he endeavored to ascertain the time required for the digestion of different articles of food.[10] The stomach of St. Martin was ruptured by the bursting of a gun. When he recovered from the effects of the accident under the surgical care of Dr. Beaumont, the stomach became adherent to the side, with an external aperture. Nature had formed a kind of valve, which closed the aperture from the interior, and thus prevented the contents of the stomach from escaping; but on pus.h.i.+ng it aside, the process of digestion could be seen. Through this opening, the appearance of the coats of the stomach and food, at different stages of digestion, were examined.
[10] The time required for the digestion of the different articles of food might vary in other persons; and would probably vary in the same individual at different periods, as the employment, health, season, &c., exert a modifying influence.
TABLE,
SHOWING THE MEAN TIME OF DIGESTION OF THE DIFFERENT ARTICLES OF DIET.
-----------------------------+--------------+-------- Articles.
Preparation.
Time
h. m.
-----------------------------+--------------+-------- Apples, sour, hard,
Raw,
2 50 Apples, sour, mellow,
Raw,
2 Apples, sweet, do.,
Raw,
1 30 Ba.s.s, striped, fresh,
Broiled,
3 Beans, pod,
Boiled,
2 30 Beef, fresh, lean, rare,
Roasted,
3 Beef, fresh, lean, dry,
Roasted,
3 30 Beef steak,
Broiled,
3 Beef, with salt only,
Boiled,
3 36 Beef, with mustard,
Boiled,
3 10 Beef, fresh, lean,
Fried,
4 Beef, old, hard, salted,
Boiled,
4 15 Beets,
Boiled,