384 THE SURVIVAL OP THE UNLIKE, [XXIV. 



ago are now known? If any of these old varieties 

 are not cultivated at the present day, what are the 

 causes of their disappearance ? In 1806, M'Mahon 

 catalogued fifty -nine varieties of apples for cultivation 

 in North America. Of these, twenty -one were offered 

 for sale in 1892. In 1817, William Coxe gave a list 

 of one hundred kinds of the best apples for cultiva- 

 tion in North America, of which forty were still 

 offered for sale in 1892. In 1845, A. J. Downing 

 described one hundred and ninety varieties of apples, 

 of which eighty -four are now offered for sale. The 

 percentages of apples in these lists which have per- 

 sisted to our time as commercial varieties are 36, 39 

 and 46 respectively. In other words, from 64 to 54 

 per cent of them have disappeared within a century. 

 Why? 



1 . Have they disappeared because of age ? We do 

 not know if any given type or species of animal or 

 plant is pre -limited in duration. It is true that 

 many of the earlier forms of life have wholly dis- 

 appeared, but this disappearance may have been due 

 to changed physical conditions to which the or- 

 ganisms were subjected, or to defeat in the struggle 

 for existence, rather than to a wearing out or 

 pre -determined death. But even if species do wear 

 out, the deterioration is so slow that it could not be 

 detected in many centuries, probably ; and it is fair 

 to assume that any such tendency would be much 

 overbalanced by the protecting care which man ex- 

 tends to all species or varieties which please him. 



But there are now sufficient records to show that 

 mere age of a variety counts for very little. The 

 White Jennetting apple was described as early as 



