1884.] Professor Huxley's Darwinism . 59 
natural selection ?” (“ Lay Sermons,” p. 298). “ How far 
‘ natural selection ’ suffices for the production of species 
remains to be seen. Few can doubt that, if not the whole 
cause, it is a very important factor in that operation ” 
(“ Science and Culture,” p. 306). “ But postulating the 
existence of living matter endowed with that power of 
hereditary transmission, and with that tendency to vary 
which is found in all such matter, Mr. Darwin has shown 
good reasons for believing that the interaction between 
living matter and surrounding conditions, which results in 
the survival of the fittest, is sufficient to account for the 
gradual evolution of plants and animals from their simplest 
to their most complicated forms, and for the known phe- 
nomena of Morphology, Physiology, and Distribution ” 
(“ Manual of the Anatomy of Invertebrated Animals,” pp. 
39 > 4°; and “ Encycl. Brit.,” art. ‘ Biology’). 
The Role of Natural Selection. 
Prof. Huxley “ never had the slightest notion ” that it 
was other than “ an iteration of the fundamental principle 
of Darwinism ” to assert that the “ aCtion of ‘ natural 
selection ’ ” is “ subordinate ” (“ Critiques and Addresses,” 
p. 299) : our author maintains that variation is of paramount 
importance, although Mr. Darwin had applied, and repeated, 
an illustration in his “ Variation under Domestication,” to 
enforce the opposite lesson (1st ed., ii., 248, 249, 430 ; 2nd 
ed., ii., 236, 426). 
The Causes of Variation. 
Prof. Huxley tells us that Mr. Darwin “ seeks for the 
principal, if not the only, cause of variation in the influence 
of changing conditions ” (“ Manual of the Anatomy of In- 
vertebrated Animals,” p. 40, and “ Encyclopaedia Britan- 
nica,” art. ‘ Biology ’), whereas Mr. Darwin tells us, in the 
“ Origin of Species,” that “ Such considerations as these 
incline me to lay less weight on the direCt aCtion of the sur- 
rounding conditions, than on a tendency to vary, due to causes 
of which we are quite ignorant ” (p. 107) ; in the “ Descent of 
Man,” that “ in general we can only say that the cause of 
each slight variation and of each monstrosity lies much 
more in the constitution of the organism than in the nature 
of the surrounding conditions ” (p. 608) ; in the “Variation 
under Domestication,” that “ these fadts are important from 
showing, as remarked in a former chapter, that each trifling 
