蛇如何制造毒液英语文章
来源:才华咖 本文已影响8.76K人
来源:才华咖 本文已影响8.76K人
How it came about that snakes manufactured poison is a mystery. Over the periods their saliva, a mild, digestive juice like our own, was converted into a poison that defies analysis even today. It was not forced upon them by the survival competition; they could have caught and lived on prey without using poison just as the thousands of non-poisonous snakes still do. Poison to a snake is merely a luxury; it enables it to get its food with very little effort, no more effort than one bite. And why only snakes ? Cats, for instance, would be greatly helped; no running rights with large, fierce rats or tussles with grown rabbits just a bite and no more effort needed. In fact it would be an assistance to all the carnivorae--though it would be a two-edged weapon -When they fought each other. But, of the vertebrates, unpredictable Nature selected only snakes (and one lizard). One wonders also why Nature, with some snakes concocted poison of such extreme potency.
In the conversion of saliva into poison one might suppose that a fixed process took place. It did not; some snakes manufactured a poison different in every respect from that of others, as different as arsenic is from strychnine, and having different effects. One poison acts on the nerves, the other on the blood.
The makers of the nerve poison include the mambas and the cobras and their venom is called neurotoxic. Vipers (adders) and rattlesnakes manufacture the blood poison, which is known as haemolytic. Both poisons are unpleasant, but by far the more unpleasant is the blood poison. It is said that the nerve poison is the more primitive of the two, that the blood poison is , so to speak, a newer product from an improved formula. Be that as it may, the nerve poison does its business with man far more quickly than the blood poison. This,however,means nothing. Snakes did not acquire their poison for use against man but for use against prey such as rats and mice, and the effects on these of viperine poison is almost immediate.
考研英语写作如何构造龙头凤尾
中小学生如何预防诺如病毒
如何通过小游戏创造英语环境
如何做好制造业的生产管理
英语文章邻居与蛇
如何定制英语写作私人模板
如何制造服装设计的空间
如何打造幼儿的英语基础训练
如何编制援外公路项目造价
论如何打造初中英语高效课堂
制造业如何应用仓储管理技术
如何写好日语文章
制造型企业如何做好采购管理
2016中考英语写作如何使文章有亮点
如何有效控制土方工程的造价
制造工厂如何做好品质管理
杯弓蛇影如何造句
如何创造良好的英语学习环境
制造工厂如何做好品质管理?
主管药师知识章节考点:液体制剂
英语句子如何连读
中国制造产业危机如何应对
如何用CAD绘制构造线
如何选购宠物蛇
中小型制造企业该如何选择