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  3. When less was known of animals and plants, the discovery of a new species wa

When less was known of animals and plants, the discovery of a new species wa

游客2023-12-31  48
问题     When less was known of animals and plants, the discovery of a new species was the great object. This is now almost the lowest kind of scientific work. The discovery of a new species as such does not change a feature in the science of natural history. It is merely adding to the enumeration of objects.
    We should look rather for the fundamental relations among animals; the number of species we may find is of importance only if they explain the distribution and limitation of different genera and families, their relations to each other and to the physical conditions under which they live. The origin of life is the great question of the day. How did the organic world come to be as it is? How did Brazil come to be inhabited by the animals and plants now living there? Who were its inhabitants in past times? What reason is there to believe that the present condition of things in this country is in any sense derived from the past?
    The first step in this investigation must be to ascertain the geographical distribution of the present animals and plants. Suppose we first examine the Rio San Francisco. The basin of this river is entirely isolated. Are its inhabitants, like its waters, completely distinct from those of other basins? Are its species peculiar to itself, and not repeated in any other river of the continent? Extraordinary as this result would seem, I nevertheless expect to find it so. The next water-basin we shall have to examine will be that of the Amazons, which connects through the Rio Negro with the Orinoco. It has been frequently repeated that the same species of fish exist in the waters of the San Francisco and in those of Guiana and of the Amazons. At all events, our works on fish constantly indicate Brazil and Guiana as the common home of many species; but this observation has never been made with sufficient accuracy.
    Fifty years ago the exact locality from which any animal came seemed an unimportant fact in its scientific history, for the bearing of this question on that of origin was not then perceived. To say that any specimen came from South America was quite enough; to specify that it came from Brazil, from the Amazons, the San Francisco, or the La Plata, seemed a marvelous accuracy in the observers. In the museum at Paris, for example, there are many specimens entered as coming from New York or from Para; but all that is absolutely known about them is that they were shipped from those seaports. Nobody knows exactly where they were collected. All this kind of investigation is far too loose for our present object. Our work must be done with much more precision.
    Therefore, my young friends who come with me on this expedition, let us be careful that every specimen has a label, recording locality and date. We must try not to mix the fish of different rivers, even though they flow into each other, but to keep our collections perfectly distinct. You will easily see the vast importance of thus ascertaining the limitation of species, and the bearing of the result on the great question of origin.  [br] The word "genera" underlined in Paragraph 2 refers to________.
选项 A、animals and plants
B、people
C、classifications
D、habitats
答案 C
解析 词义界定。本题依然需要借助语境推知画线词的意思，画线词语境为“the distribution and limitation of different genera and families”，前面讲分布与局限，后面并列的词汇为“族群”，并被different修饰，因此classifications(类别)符合语境。
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