MANUAL WORK. 395 



Darwin, and several others were fully aware of 

 the variability of species ; they were opening 

 the way for the construction of biology on the 

 principles of variation ; but here, again, half a 

 century was wasted before the variability of 

 species was brought again to the front ; and we 

 all remember how Darwin's ideas were carried 

 on and forced on the attention of university 

 people, chiefly by persons who were not pro- 

 fessional scientists themselves ; and yet in 

 Darwin's hands the theory of evolution surely 

 was narrowed, owing to the overwhelming 

 importance given to only one factor of evolution. 

 For many years past astronomy has been 

 needing a careful revision of the Kant and 

 Laplace's hypothesis ; but no theory is yet 

 forthcoming which would compel general ac- 

 ceptance. Geology surely has made wonderful 

 progress in the reconstitution of the palseon- 

 tological record, but dynamical geology pro- 

 gresses at a despairingly slow rate ; while all 

 future progress in the great question as to 

 the laws of distribution of living organisms 

 on the surface of the earth is hampered by 

 the want of knowledge as to the extension of 

 glaciation during the Quaternary epoch.* 



* The rate of progress in the recently so popular Glacial 

 Period question was strikingly slow. Already Venetz in 1821 

 and Esmarck in 1823 had explained the erratic phenomena by 



