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are so indeterminate, that it is frequently difficult, and 

 sometimes impossible, to say whetlier a lowly organism 

 should be classed with animals or plants — a fact which led 

 Haeckel to propose a new kingdom for such forms, that 

 of the Protista. 



Whatever gaps there are in the organic series are con- 

 stantly being filled up by discoveries of living or extinct 

 animals and the essential nature of their structure. Nor is 

 this all. Why should the higher animals have seven cervical 

 vertebrse and no more, except by reason of descent ? Why 

 should all vertebrates have not more than two pairs of limbs 

 — so that the monkey is obliged to develop the resources of 

 his tail ? I know of no sufficient answer but that given by 

 Darwin. It is difficult, on any other assumption, to under- 

 stand either the remarkable ease with which certain animals 

 and plants fall into their natural orders, or the remark- 

 able difficulty in separating certain other orders, or the 

 impossibility of agreement as to the species of certain large 

 genera. 



Is there any other explanation that will account for the 

 fact that the young batrachian has gills like a fish ; that 

 the wingless dodo was nevertheless structurally a bird ; that 

 the ornithorhynchus and the echidna, though essentially 

 mammalia, approximate to the bird type ; that any natural 

 classification is possible at all ? 



What would you think of a modern scholar who should 

 doubt the common origin of the Indo-European family of 

 languages and deride Grimm's law. More than Grimm 

 did for philology has Darwin done for natural history. 

 Just as certainly as the similarities of the Aryan tongue 

 point to a common Aryan origin, so surely do the simila- 

 rities of animals and plants point to a common descent. 

 And as the bonds of connection between tongues are to be 

 found not merely in living languages, but in fossil forms 

 of speech — in Greek, in Latin, in Sanskrit — so every year 

 supplies us with fresh links that are missing in the series 

 of organic life by the discovery of new fossil forms. 



This brings us to our Sixth great argument, the Geological. 

 I have more than once referred to geological facts in the 

 consideration of other aspects of the question before us, and 

 I will now state, as concisely as may be, certain geological 

 facts which bear very directly on Darwinism. Fossils from 

 the later tertiary periods are closely allied to their living 

 representatives of the same area. For example, the fossil 



