Hybrids

Examples

• The variability, however, in the successive generations of mongrels is, perhaps, greater than in hybrids. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Many exotic plants have pollen utterly worthless, in the same condition as in the most sterile hybrids. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• We see this tendency to become striped most strongly displayed in hybrids from between several of the most distinct species. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• The above view of the sterility of hybrids being caused by two constitutions being compounded into one has been strongly maintained by Max Wichura. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• In regard to the sterility of hybrids, in which the sexual elements are imperfectly developed, the case is somewhat different. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Altogether there is the closest identity in character and behaviour between illegitimate plants and hybrids. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• This greater variability in mongrels than in hybrids does not seem at all surprising. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• So it is with hybrids, for their offspring in successive generations are eminently liable to vary, as every experimentalist has observed. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• The fertility, both of first crosses and of hybrids, is more easily affected by unfavourable conditions, than is that of pure species. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• We will now look a little closer at the probable nature of the differences between species which induce sterility in first crosses and in hybrids. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• It is not always equal in degree in a first cross and in the hybrids produced from this cross. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• From this extreme degree of sterility we have self-fertilised hybrids producing a greater and greater number of seeds up to perfect fertility. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Quatrefages states that the hybrids from two moths (Bombyx cynthia and arrindia) were proved in Paris to be fertile inter se for eight generations. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Why, it may even be asked, has the production of hybrids been permitted? Charles Darwin. On the Origin of Species by Means of Natural Selection.
• With hybrids raised from the same seed-capsule the degree of sterility is innately variable, so it is in a marked manner with illegitimate plants. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• We will now consider a little more in detail the laws governing the sterility of first crosses and of hybrids. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• The hybrids, moreover, produced from reciprocal crosses often differ in fertility. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Between the sterility thus superinduced and that of hybrids, there are many points of similarity. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Now the fertility of first crosses, and of the hybrids produced from them, is largely governed by their systematic affinity. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• And in this case, it is not at all surprising that the inherent sterility in the hybrids should have gone on increasing. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• First crosses between forms, sufficiently distinct to be ranked as species, and their hybrids, are very generally, but not universally, sterile. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Both hybrids and mongrels can be reduced to either pure parent form, by repeated crosses in successive generations with either parent. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• Now, hardly any cases have been ascertained with certainty of hybrids from two quite distinct species of animals being perfectly fertile. Charles Darwin. On the Origin of Species by Means of Natural Selection.
• He who will explain these latter cases will be able to explain the sterility of hybrids. Charles Darwin. On the Origin of Species by Means of Natural Selection.

Edited by Jonathan