国产精品第_久久精品国产一区二区三_99久精品_久久精品区_91视频18_国产91精品在线观看

初中英语 学英语,练听力,上听力课堂! 注册 登录
> 初中英语 > 初中英语教材 > 英文科学读本(六册全) >  第268篇

英文科学读本 第六册·Lesson 13 Animals Useful for Food

所属教程:英文科学读本(六册全)

浏览:

2022年07月16日

手机版
扫描二维码方便学习和分享

Lesson 13 Animals Useful for Food

In dealing with the vegetable food-stuffs we took bread in some form to be man's staple food. We commenced our investigation of these vegetable foods by examining the composition of wheaten bread, and we found that every kind of bread must contain similar materials, and possess similar nutritive properties.

We shall now follow the same plan in dealing with flesh foods, taking a piece of lean beef for our first investigation. If we get a piece of newly-cut lean beef, fresh from the butcher, we find that it is moist. This is due to the water which the flesh contains. We must get rid of this water before we can learn anything about the composition of the beef. The best plan is to let it dry slowly on a tin plate in the hot sun. The water will evaporate gradually, leaving the meat dry.

As the drying goes on the beef shrinks considerably in size. In fact, if the original piece weighed a pound, we should have, after the drying, less than a quarter of a pound of perfectly dry flesh. That is to say, three-quarters of its weight is water.

We can find out by experiment what are the constituents of the dry flesh. A piece of fresh beef has a red appearance, owing to the blood which it contains. We can easily get rid of the blood by repeatedly washing the flesh in fresh water, and it will then be seen to consist of a mass of whitish fibers or threads, with little particles of fat interspersed among the fibers.

If this be put into spirits of wine, the fat will all dissolve out of it, and nothing will remain but the fibrous tissue, which is the principal solid constituent of the muscles, or lean flesh, of animals. It is known in the scientific world as myosin.

When we eat meat it is this part of it—myosin—that becomes tissue-forming food. It is the nutritive part of flesh food, as gluten is of vegetable food. In fact, myosin of flesh and gluten of the vegetable may be considered as identical in this respect.

Lean meat, however, contains nearly three times as much flesh-forming material as bread. It contains no starch, while bread has half its entire weight of this material.

Civilised man in all parts of the world has always reared and kept certain animals for food. To distinguish these from the wild animals of the chase, we speak of them as domesticated animals. The chief of them are the ox, the sheep, and the pig. The cow not only provides us with flesh food when dead, but also while living gives milk. Milk is in itself a valuable food; we use it in its simple form, and we convert it into butter and cheese.

The flesh of the sheep is eaten only as fresh mutton; the pig's flesh is not only eaten fresh, but it is salted, smoked, and cured into bacon and hams.

Poultry, eggs, and game form important items in our animal food. In addition to Englands home-supply they import poultry very largely from other countries, especially from France. In 1886 England spent on eggs alone £2,879,000, most of the eggs coming from France.

Fish of various kinds must be reckoned among the important articles of the food-supply; the fisheries of Great Britain are a source of great wealth to the country. The cod, herring, mackerel, salmon, haddock, and pilchard are among the most valuable catches, and oyster cultivation is prosecuted on various parts of the coast. The herring fishery is carried on chiefly round the Scotch coasts; the pilchard fishery is confined to the southwestern corner of the island.

In 1887 it was estimated that 125,000 men and 32,000 boats were actively engaged in the British fisheries. The most valuable of the British fishing-grounds is the Dogger Bank, between England and Holland.

Among the most important and productive fisheries of the world are those of Newfoundland, Nova Scotia, and New Brunswick. Cod is the chief fish caught, but the Gulf of St. Lawrence absolutely teems with fish of almost every variety.

The annual value of these Canadian fisheries varies from four to six millions sterling.


用户搜索

疯狂英语 英语语法 新概念英语 走遍美国 四级听力 英语音标 英语入门 发音 美语 四级 新东方 七年级 赖世雄 zero是什么意思新乡市河南师范大学家属院英语学习交流群

  • 频道推荐
  • |
  • 全站推荐
  • 推荐下载
  • 网站推荐
主站蜘蛛池模板: 亚洲欧美国产视频 | 两女女百合互慰av赤裸无遮挡 | 日韩欧美一区二区三区四区 | 亚洲伊人久久大香线蕉影院 | 亚洲www啪成人一区二区麻豆 | 午夜视频a | 欧美激情精品久久久久久久九九九 | 亚洲一区视频 | 天天干天天做天天操 | aaa国产一级毛片 | 国产精品不卡高清在线观看 | 日韩在线观看一区二区不卡视频 | 欧美一级视 | 久久久久久九九 | 亚洲av无码国产综合专区 | 欧美2区| 国产6080一级毛片 | 天天草天天草 | 欧美作爱福利免费观看视频 | 全球中文成人在线 | 韩国美女vip福利视频在线看 | 亚洲一区在线日韩在线深爱 | 深夜桃色影院 | 伊人精品久久久久中文字幕 | 国产成人午夜精华液 | 国产亚洲女在线精品 | 麻豆国产人免费人成免费视频 | 国产亚洲精品第一综合麻豆 | 99久久一香蕉国产线看观看 | 在线观看亚洲精品国产 | 亚洲国产99999在线精品一区 | 国产精品国产三级国产专播下 | 日本强伦姧熟睡人妻完整视频 | 丰满的邻居hd高清伦理 | 中文字幕人妻无码一夲道 | 男人天堂免费 | 青娱乐免费视频在线观看 | 911亚洲国产自产 | 萌白酱香蕉白丝护士服喷浆 | 亚洲av成人无码精品网站老司机 | 精品亚洲欧美中文字幕在线看 |