202 MISCELLANEOUS OBJECTIONS TO THE [Chap. VII.. 



indicated by Mr. Mivart, are as follows. According to our expe- 

 rience, abrupt and strongly marked variations occur in our domesti- 

 cated productions, singly and at rather long intervals of time. I f 

 sucli occurred under nature, they would be liable, as formerly 

 explained, to be lost by accidental causes of destruction and by 

 subsequent inter-crossing ; and so it is known to be under domesti- 

 cation, unless abrupt variations of this kind are specially preserved 

 and separated by the care of man. Hence in order that a new 

 species should suddenly appear in the manner supposed by Mr. 

 Mivart, it is almost necessary to believe, in opposition to all ana- 

 logy, that several wonderfully changed individuals appeared simul- 

 taneously within the same district. This difficulty, as in the case of 

 unconscious selection by man, is avoided on the theory of gradual 

 evolution, through the preservation of a large number of individuals, 

 which varied more or less in any favourable direction, and of the 

 destruction of a large number which varied in an opposite manner. 



That many species have been evolved in an extremely gradual 

 manner, there can hardly be a doubt. The species and even the 

 genera of many large natural families are so closely allied together, 

 that it is difficult to distinguish not a few of them. On every con- 

 tinent in proceeding from north to south, from lowland to upland, 

 &c, we meet with a host of closely related or representative species ; 

 as we likewise do on certain distinct continents, which we have 

 reason to believe were formerly connected. But in making these 

 and the following remarks, I am compelled to allude to subjects 

 hereafter to be discussed. Look at the many outlying islands round 

 a continent, and see how many of their inhabitants can be raised 

 only to the rank of doubtful species. So it is if we look to past 

 times, and compare the species which have just passed away with 

 those still living within the same areas ; or if we compare the fossil 

 species embedded in the sub-stages of the same geological formation. 

 It is indeed manifest that multitudes of species are related in the 

 closest manner to other species that still exist, or have lately 

 existed ; and it will hardly be maintained that such species have 

 been developed in an abrupt or sudden manner. Nor should it be 

 forgotten, when we look to the special parts of allied species, instead 

 of to distinct species, that numerous and wonderfully fine grada- 

 tions can be traced, connecting together widely different structures. 



Many large groups of facts are intelligible only on the principle 

 that species have been evolved by very small steps. For instance, 

 the fact that the species included in the larger genera are more closely 

 related to each other, and present a greater number of varieties 

 thaj do the species in the smaller genera. The former are also 



