Thus structure must be known to understand function, and function known enables us to interpret structure. Evolution could not be demonstrated until after there had been gathered the necessary materials to show relations of different organisms, past and present. But, evolution known, and vast arrays of structure become intelligible. Without the knowledge of organic distribution no laws of distribution could be framed, but without the explanation of distribution afforded by evolution the facts are an unmeaning puzzle. So, too, without an effort at systematic arrangement of plant and animal forms no fundamental law of relationship could have been discovered, but given a law of relationship and systematic biology assumes a totally different aspect. Recognition of the multitudinous forms of nature are but one step then in the presentation of the vast concourse in their proper relations. No doubt biologists will persist till every form of life has been adequately described and some means of designating it adopted. So much may be expected from the enthusiasm of the systematist. Some centuries of effort must, of course, be expected to elapse before the task is done. But it is evident that the modern biology is much less concerned in the mere recognition of these innumerable forms of life, these remotest expressions of the force of evolution, than in the gaining of some adequate conception of their relations, the forces of adaptation that have fitted them for their particular niche in the realm of nature, their relation to the other organisms with which they are associated and which constitute for them a source of support or a menace to existence. That is, modern biology concerns itself not only with the elements of structure in the organism, with the means it has of performing its varied functions with the aggregate of individuals which constitute its species, but goes on to its relations to all the influences and forces which have made it what it is and which sustain its specific existence. Less than this is too narrow a view of the province of biology. Here is unlimited scope for the student who pursues knowledge for love of knowledge.