CONTENTS xi 



CHAPTER PAGE 



VII. Influence of Temperature upon Living Matter . . . 254 



VIII. Effect of Chemical Agents upon Protoplasmic Activity . . 264 

 IX. Effect of Saline Solution upon Development in Aquatic 



Animals . 282 



X. Influence of Use and Disuse upon Development . . . 285 



XI. External Influences as Causes of Variation in Type . . 290 



References . 294 



X. RELATIVE STABILITY AND INSTABILITY OF LIVING MATTER , . 295 



I. Evidence from Stability of Type 296 



II. Evidence from Mutability of Species ... . 298 

 ITI. Evidence from Reversion and Atavism 305 



IV. Evidence from Disappearance of Parts . ... . 306 



V. Evidence from the Direct Action of the Environment . . 307 



VI. Evidence from Acclimatization . . . . . . 308 



VII. Evidence from Regeneration 316 



VIII. Internal Factors in Regeneration 332 



IX. Evidence from Grafting . . .- 335 



X. Evidence from the Origin of New Cells and Tissues . -336 



XI. Evidence from Development and Differentiation . . . 338 



References . 345 



PART III TRANSMISSION 



XI. TRANSMISSION OF MODIFICATIONS DUE TO EXTERNAL INFLUENCES 348 



I. Introductory 348 



II. P>idence from the Nature of Variation . . . . 356 



III. Evidence from Mutilations . . . . .'.'*'. . 364 



IV. Evidence from Food Supply 370 



V. Evidence from Acclimatization 374 



VI. Evidence from Habit and Instinct 386 



VII. Evidence from Use and Disuse 404 



VIII. Evidence from Disappearing Organs ..... 409 

 IX. Variations due to Causes not affecting the Germ are not 



Transmitted . . 416 



References . . . 418 



XII. TYPE AND VARIABILITY 419 



I. Type 420 



II. Variability, or Deviation from Type 425 



III. Practical Hints on the Taking and Grouping of Measurements 435 



IV. Probable Error 437 



V. Comparative Type and Variability for Different Characters in 



the Same Population . . 444 



VI. Effect of Selection upon Type and Variability . . . 445 



VII. Indirect Effects of Selection upon Type and Variability . . 447 

 VIII. Studies in Type and Variability of the Same Variety of Corn 



raised under Different Conditions as to Fertility . . . 449 



References 452 



