Alfred Russel Wallace 



—gave much satisfaction both to Lyell and to Darwin. 

 The underlying argument was a combination of the views 

 held by Sir Charles Lyell and Mr. Croll respectively in re- 

 lation to the glacial epoch, and the great effect of changed 

 distribution of sea and land, or of differences of altitude, 

 and how by combining the two a better explanation could 

 be arrived at than by accepting each theory on its own basis. 

 His next publication of importance was the volume en- 

 titled '' Contributions to the Theory of Natural Selection," 

 consisting of ten essays (all of which had previously appeared 

 in various periodicals) arranged in the following order : 



1. On the Law which has regulated the Introduction of 

 New Species. 



2. On the Tendency of Varieties to depart indefinitely 

 from the Original Type. 



3. Mimicry, and other Protective Resemblances among 

 Animals. 



4. The Malayan Papilionidse. 



5. Instinct in Man and Animals. 



6. The Philosophy of Birds' Nests. 



7. A Theory of Birds' Nests. 



8. Creation by Law. 



9. The Development of Human Races under the Law of 

 Natural Selection. 



10. The Limits of Natural Selection as applied to Man. 



His reasons for publishing this work were, first, that 

 the first two papers of the series had gained him the re- 

 putation of being an originator of the theory of Natural 

 Selection, and, secondly, that there were a few important 

 points relating to the origin of life and consciousness 

 and the mental and moral qualities of man and other 

 views on which he entirely differed from Darwin. 



Though in later years Wallace's convictions developed 

 considerably with regard to the spiritual aspect of man's 



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