 The intermixture of distinct species is guarded against by the aversion of the individuals composing them to sexual union, or by the sterility of the mule offspring. It does not appear that true hybrid races have ever been perpetuated for several generations,...  Life on the Earth: Its Origin and Succession - עמוד 186מאת John Phillips - 1860 - 224 דפיםתצוגה מלאה - מידע על ספר זה
 | Sir Charles Lyell - 1832 - 368 דפים
...beyond the defined limits being fatal to the existence of the individual. Sthly. The intermixture of distinct species is guarded against by the aversion...and not to the intermixture of hybrid with hybrid. 6thly. From the above considerations, it appears that species have a real existence in nature, and... | |
 | Benjamin Godwin - 1834 - 314 דפים
...beyond the defined limits being fatal to the existence of the individual. " oth ly, The intermixture of distinct species is guarded against by the aversion...and not to the intermixture of hybrid with hybrid. "6thly, From the above considerations, it appears that species have a real existence in nature, and... | |
 | Benjamin Godwin - 1835 - 410 דפים
...beyond the defined limits being fatal to the existence of the individual. " 5thly. The intermixture of distinct species is guarded against by the aversion...mules with individuals of pure species, and not to the intermixure of hybrid with hybrid. " 6thly. From the above considerations, it appears that species... | |
 | Sir Charles Lyell - 1837 - 568 דפים
...beyond the defined limits being fatal lo the existence of the individual. Sthly. The intermixture of distinct species is guarded against by the aversion...perpetuated for several generations, even by the assistance * E. R- A. Serres, Anatomic Compare du Cerveau, illustrated by numerous plates, tome i., 1824. of man... | |
 | 1850 - 600 דפים
...beyond the defined limits being fatal to the existence of the individual. " 5th. The intermixture of distinct species is guarded against by the aversion...relate to the crossing of mules with individuals of the pure species, and not to the intermixture of hybrid with hybrid. " 6th. From these considerations... | |
 | John Holmes Agnew, Walter Hilliard Bidwell - 1850 - 604 דפים
...beyond the defined limits being fatal to the existence of the individual. " 5th. The intermixture of distinct species is guarded against by the aversion...sterility of the mule offspring. It does not appear tiiat true hybrid races have ever been perpetmted for several generations, even by the assistance of... | |
 | 1857 - 520 דפים
...beyond the defined limits being fatal to the existence of the individual. " 5thly. The intermixture of distinct species is guarded against by the aversion...and not to the intermixture of hybrid with hybrid. "6thly. From the above considerations, it appears that species have a real existence in nature ; and... | |
 | Thomas Ragg - 1858 - 456 דפים
...beyond the defined limits being fatal to the existence of the individual. "5thly. The intermixture of distinct species is guarded against by the aversion...of man ; for the cases usually cited relate to the crossings of mules with individuals of pure species, and not to the intermixture of hybrid with hybrid.... | |
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