IV CONTENTS. 



NEWLT-ACQUTKED CHARACTERS IN OUR DOMESTICATED AISTEMALS 

 OFTEN TRANSMITTED BY ONE SEX ALONE, SOMETIMES LOST BY ONE 



SEX ALONE INHERITANCE AT CORRESPONDING PERIODS OF LIFE 



THE IMPORTANCE OF THE PRINCIPLE WITH RESPECT TO EMBRY- 

 OLOGY ; AS EXHIBITED IN DOMESTICATED ANIMALS ; AS EXHIBITED 

 IN THE APPEARANCE AND DISAPPEARANCE OF INHERITED DIS- 

 EASES; SOMETIMES SUPERVENING EARLIER IN THE CHILD THAN 

 IN THE PARENT — SUMMARY OF THE THREE PRECEDING CHAPTERS. 



Pages 37-61 



CHAPTEK XV. 



ON CROSSING. 



FREE INTERCROSSING OBLITERATES THE DIFFERENCES BETWEEN ALLIED 

 BREEDS — WHEN THE NUMBERS OF TWO COMMINGLING BREEDS ARE 

 UNEQUAL, ONE ABSORBS THE OTHER — THE RATE OF ABSORPTION 

 DETERMINED BY PREPOTENCY OF TRANSMISSION, BY THE CON- 

 DITIONS OF LIFE, AND BY NATURAL SELECTION — ALL ORGANIC 

 BEINGS OCCASIONALLY INTERCROSS ; APPARENT EXCEPTIONS — ON 

 CERTAIN CHARACTERS INCAPABLE OF FUSION ; CHIEFLY OR EX- 

 CLUSIVELY THOSE WHICH HAVE SUDDENLY APPEARED IN THE IN- 

 DIVIDUAL — ON THE MODIFICATION OF OLD RACES, AND THE 

 FORMATION OF NEW RACES, BY CROSSING — SOME CROSSED RACES 

 HAVE BRED TRUE FROM THEIR FIRST PRODUCTION — ON THE CROSS- 

 ING OF DISTINCT SPECIES IN RELATION TO THE FORMATION OF 

 DOMESTIC RACES 62-77 



CHAPTEK XVI. 



CAUSES WHICH INTERFERE WITH THE FREE CROSSING OF 

 VARIETIES — INFLUENCE OF DOMESTICATION ON FER- 

 TILITY. 



DIFFICULTIES IN JUDGING OF THE FERTILITY OF VARIETIES AVHEN 

 CROSSED — VARIOUS CAUSES WHICH KEEP VARIETIES DISTINCT, AS 

 THE PERIOD OF BREEDING AND SEXUAL PREFERENCE — VARIETIES 

 OF WHEAT SAID TO BE STERILE WHEN CROSSED — VARIETIES OF 

 MAIZE, VERBASCUM, HOLLYHOCK, GOURDS, MELONS, AND TOBACCO 



