Book contents
- Frontmatter
- Contents
- CHAPTER XII INHERITANCE
- CHAPTER XIII INHERITANCE continued – REVERSION OR ATAVISM
- CHAPTER XIV INHERITANCE continued – FIXEDNESS OF CHARACTER – PREPOTENCY – SEXUAL LIMITATION – CORRESPONDENCE OF AGE
- CHAPTER XV ON CROSSING
- CHAPTER XVI CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF VARIETIES – INFLUENCE OF DOMESTICATION ON FERTILITY
- CHAPTER XVII ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL EFFECTS OF CLOSE INTERBREEDING
- CHAPTER XVIII ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED CONDITIONS OF LIFE: STERILITY FROM VARIOUS CAUSES
- CHAPTER XIX SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS ON HYBRIDISM
- CHAPTER XX SELECTION BY MAN
- CHAPTER XXI SELECTION–continued
- CHAPTER XXII CAUSES OF VARIABILITY
- CHAPTER XXIII DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF LIFE
- CHAPTER XXIV LAWS OF VARIATION – USE AND DISUSE, ETC
- CHAPTER XXV LAWS OF VARIATION, continued – CORRELATED VARIABILITY
- CHAPTER XXVI LAWS OF VARIATION, continued – SUMMARY
- CHAPTER XXVII PROVISIONAL HYPOTHESIS OF PANGENESIS
- CHAPTER XXVIII CONCLUDING REMARKS
- INDEX
CHAPTER XVI - CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF VARIETIES – INFLUENCE OF DOMESTICATION ON FERTILITY
Published online by Cambridge University Press: 05 July 2011
- Frontmatter
- Contents
- CHAPTER XII INHERITANCE
- CHAPTER XIII INHERITANCE continued – REVERSION OR ATAVISM
- CHAPTER XIV INHERITANCE continued – FIXEDNESS OF CHARACTER – PREPOTENCY – SEXUAL LIMITATION – CORRESPONDENCE OF AGE
- CHAPTER XV ON CROSSING
- CHAPTER XVI CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF VARIETIES – INFLUENCE OF DOMESTICATION ON FERTILITY
- CHAPTER XVII ON THE GOOD EFFECTS OF CROSSING, AND ON THE EVIL EFFECTS OF CLOSE INTERBREEDING
- CHAPTER XVIII ON THE ADVANTAGES AND DISADVANTAGES OF CHANGED CONDITIONS OF LIFE: STERILITY FROM VARIOUS CAUSES
- CHAPTER XIX SUMMARY OF THE FOUR LAST CHAPTERS, WITH REMARKS ON HYBRIDISM
- CHAPTER XX SELECTION BY MAN
- CHAPTER XXI SELECTION–continued
- CHAPTER XXII CAUSES OF VARIABILITY
- CHAPTER XXIII DIRECT AND DEFINITE ACTION OF THE EXTERNAL CONDITIONS OF LIFE
- CHAPTER XXIV LAWS OF VARIATION – USE AND DISUSE, ETC
- CHAPTER XXV LAWS OF VARIATION, continued – CORRELATED VARIABILITY
- CHAPTER XXVI LAWS OF VARIATION, continued – SUMMARY
- CHAPTER XXVII PROVISIONAL HYPOTHESIS OF PANGENESIS
- CHAPTER XXVIII CONCLUDING REMARKS
- INDEX
Summary
The domesticated races of both animals and plants, when crossed, are with extremely few exceptions quite prolific,–in some cases even more so than the purely bred parent-races. The offspring, also, raised from such crosses are likewise, as we shall see in the following chapter; generally more vigorous and fertile than their parents. On the other hand, species when crossed, and their hybrid offspring, are almost invariably in some degree sterile; and here there seems to exist a broad and insuperable distinction between races and species. The importance of this subject as bearing on the origin of species is obvious; and we shall hereafter recur to it.
It is unfortunate how few precise observations have been made on the fertility of mongrel animals and plants during several successive generations. Dr. Broca has remarked that no one has observed whether, for instance, mongrel dogs, bred inter se, are indefinitely fertile; yet, if a shade of infertility be detected by careful observation in the offspring of natural forms when crossed, it is thought that their specific distinction is proved. But so many breeds of sheep, cattle, pigs, dogs, and poultry, have been crossed and recrossed in various ways, that any sterility, if it had existed, would from being injurious almost certainly have been observed. In investigating the fertility of crossed varieties many sources of doubt occur.
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- The Variation of Animals and Plants under Domestication , pp. 100 - 113Publisher: Cambridge University PressPrint publication year: 2010First published in: 1868