WHAT IS THE ORIGIN OF SPECIES? 199 



organisms themselves, manifested in the original discontinuity 

 of variation." * 



It is certain that more light is required upon these funda- 

 mental factors of evolution before the final word can be said 

 upon the origin of species. That which distinguishes the 

 species, in contrast to the variety, is the constancy of transmis- 

 sion of its specific characters, but it is evident that constancy 

 here is not absolute constancy at least it is not known to 

 be absolute. 



In variation, the nature, causes, degrees, and rate of 

 variation are the subjects of investigation which now promise 

 to give the true explanation of not only the nature but the 

 origin of species. 



* " Materials for the Study of Variation, treated with especial regard to- 

 Discontinuity in the origin of species," by William Bateson, London, 1894, p. 

 567. 



