244 THE HYPOTHESIS CONSIDERED IN CONNEXION WITH THE AFFINITIES AND GEOGRAPHICAL DISTRIBUTION OF ANIMALS. In the preceding chapters allusion has been re peatedly made to the gradation observed in the forms of the various beings composing the organic kingdoms, from the simple infusoria and fuci up to the highest mammals and dicotyledons. Upon such a gradation the whole of this theory depends, and it therefore is desirable that a view of it should be given in the present place, however briefly. In the words of Mr. Rymer Jones, “from what ever form or race of animals we advance towards the next succeeding it in the great scale of Nature, we find ourselves insensibly led on by such gentle gradations, as to make the transition from class to
