CONTENTS. 



b. Normal Articulations 283 



I.. The Physiology of Bone Moulding 285 



i. Moulding of the Articulations 287 



a. The Limb Articulations . .... . . 287 



b. The Forms of Vertebral Centra . .... 302 

 i. Increase of Size Through Use 304 



a. The Proportions of the Limbs and their Segments 305 



b. The Number of the Digits . 309 



c. The Horns ... 314 



1. Mechanical Origin of Dental Types . . . . 318 



Preliminary ... 318 



a. The Origin of Canine Teeth .... . . 327 



The Development of the Incisors 328 



b. 

 c. 

 d. 

 e. 



The Development of Molars .... . 331 



Origin of the Carnivorous Dentition . . . 332 



Origin of the Dental Type of the Glires .... 345 



V. Disuse in Mammalia . 352 



a. Natatory Limbs 352 



b. Abortion of Phalanges in Ungulata ... . 353 



c. Atrophy of Ulna and Fibula .... . . 355 



d. Atrophy of Incisor Teeth 356 



vi. Homoplassy in Mammalia 357 



vii. Origin of the Divisions of Vertebrata 362 



5. Objections to Kinetogenesis 375 



Chapter VII. Natural Selection 385 



PART III. THE INHERITANCE OF VARIATION. 



Preliminary 397 



Chapter VIII. Heredity. 



1. The Question Stated . . .... . . 398 



2. Evidence from Embryology . . . . ... 401 



u. Vertebrata . . . . . 401 



b. Arthropoda ... .... .... 404 



3. Evidence from Paleontology . . 405 



u. The Impressed Zone of the Nautiloids . . 405 



4. Evidence from Breeding 422 



u. Of Characters Due to Nutrition . . . . 423 



b. Of Characters Due to Exercise of Function . . 426 



e. Of Characters Due to Disease 430 



