And here I have to express my very special obligations to Mr. Darwin, who not only assisted me in the most generous manner with his immense stores of information, as well as with his valuable judgment on sundry points of difficulty, but has also been kind enough to place at my disposal all the notes and clippings on animal intelligence which he has been collecting for the last forty years, together with the original MS. of his wonderful chapter on 'Instinct.' This chapter, on being re-cast for the 'Origin of Species,' underwent so merciless an amount of compression that the original draft constitutes a rich store of hitherto unpublished material. In my second work I shall have occasion to draw upon this store more largely than in the present one, and it is needless to add that in all cases where I do draw upon it I shall be careful to state the source to which I am indebted. [The above was written when I sent this work to the publishers several months ago, and I have thought it best to leave the concluding paragraph as it originally stood. But in making this explanation, I cannot allude to the calamity which has since occurred without paying my tribute, not alone to the memory of the greatest genius of our age, but still more, and much more, to the memory of a friend so inexpressibly noble, kind, and generous, that even my immense admiration of the naturalist was surpassed by my loving veneration for the man.] FOOTNOTES: [1] Letters may be addressed to me directly at 18 Cornwall Terrace, Regent's Park, London, N W. CONTENTS. PAGE INTRODUCTION 1 CHAPTER I. APPLICATION OF THE FOREGOING PRINCIPLES TO THE LOWEST ANIMALS 18 CHAPTER II. MOLLUSCA 25 CHAPTER III. ANTS 31 CHAPTER IV. BEES AND WASPS 143 CHAPTER V. TERMITES 198 CHAPTER VI. SPIDERS AND SCORPIONS 204 CHAPTER VII. REMAINING ARTICULATA 226 CHAPTER VIII. FISH 241 CHAPTER IX. BATRACHIANS AND REPTILES 254 CHAPTER X. BIRDS 266 CHAPTER XI. MAMMALS 326 CHAPTER XII. RODENTS 353 CHAPTER XIII. ELEPHANT 386 CHAPTER XIV. THE CAT 411 CHAPTER XV. FOXES, WOLVES, JACKALS, &C. 426