DARWIN. l8i 



the study of a very large number of specimens belonging 

 to these four specific types has convinced me that each of 

 these characters may vary independently, and that, con- 

 sequently, certain individuals exhibit a combination of 

 characters belonging to two distinct types. It is there- 

 fore impossible to establish clearly defined barriers sep- 

 arating these two types. The genus Angiiilla exhibits, 

 then, a phenomenon which is found in many other genera, 

 and even in the genus Homo itself, and which can be 

 explained in only two ways : Either these four forms have 

 had a common origin and are races merely, and not spe- 

 cies ; or else they are distinct in origin and are true species, 

 but have been more or less commingled, and have pro- 

 duced by their mingling intermediate forms, which co- 

 exist with those which were primitive. Science is not in 

 the position to decide between these two alternatives." 



It is on idle problems like this as to the reality 

 of species that the strength of naturalists of the 

 past century has been largely wasted. Which of 

 the forms we study are species, and therefore 

 represent separate acts of the Creator, and which 

 are mere varieties, chance products of varying 

 surroundings, and therefore to be despised and 

 ignored? Scarcely ever did two earnest students 

 of any group reach an agreement in this respect, 

 for agreement is only possible when material is lack- 

 ing. A single additional specimen often unsettles 

 every conclusion, and the contents of all museums 

 are but the slightest fragment of the life of the 

 globe. ''We can only predicate and define spe- 

 cies at all," says Dr. Coues, " from the mere cir- 

 cumstance of missing links. Our species are the 

 twigs of a tree separated from the parent stem. 



