1893. NATURAL SELECTION AND LAMARCKISM. 345 



surface, it is minutely ascertaining the texture, so to speak, of the 

 organic or inorganic substances submitted to the ordeal of its keen 

 judgment, and by the general structure and softness of the particles 

 or fibres it determines whether they shall be accepted as digestible 

 food or avoided as injurious or innutritious. It detects and rejects 

 sand, earth, grass, leaves, or other unpromising material with which 

 men from mere laziness, or the pressure of famine, would otherwise 

 gratify their hunger, to the injury of the whole system." It discovers 

 and enables us to remove such objects as fish-bones, hair, feathers, 

 and pieces of grit (which latter, as I have personally experienced, may 

 splinter a tooth) and so saves internal organs from injury by their 

 accumulation or friction, and from waste of digestive activities. The 

 tongue also delicately manipulates the food, and secures its proper 

 mastication by pushing it between the teeth, while carefully avoiding 

 being bitten between the little grinding mills and cutting m.achines 

 amid which it works so deftly and yet so safely. It is the highly 

 and wonderfully discriminative guardian and janitor of the whole 

 alimentary canal, and the supreme judge of the quality, composition, 

 and admissibility of the nutriment which is the foremost essential of 

 life. If Natural Selection cannot evolve a very special degree of 

 sensitiveness in the tongue, it is hard to see what it can evolve. Mr. 

 Spencer, however, contends that " no advantage is gained" by the 

 explorations of the tongue, that the extreme perceptiveness of its tip 

 is not needed, that use-inheritance furnishes the only possible explana- 

 tion, and that even if tactile sensibility is of use in detecting fish-bones 

 and foreign bodies among the food, a degree of sensitiveness equal to 

 that of the finger-tip (which is only half as sensitive as the tongue-tip) 

 would have been sufficient. But who can fairly undertake to decide 

 that the higher degree of sensitiveness in an important food-selecting 

 organ would never promote the well-being of individuals so far as to 

 lead to survival where others perished ? If, moreover, lower powers 

 occasionally led to elimination while surplus powers did not, there 

 might easily be an evolution of surplus powers — a principle which will 

 help to explain many of our keener and finer powers of eye and ear 

 and brain, and the surplus powers of organs generally. 



In all cases of minor advantages, especially those of economy 

 and lightness, it must constantly be borne in mind that the survival 

 test acts more specially and most strongly in occasional crises — such 

 as those of illness, famine, war, accident, and other perils— through 

 some of which all of us still have to pass from infancy onwards. In 

 such cases, exceedingly minute advantages may sometimes turn the 

 scales of life and death. Even now, although the rigour of Natural 

 Selection is so greatly mitigated under civilisation, a slightly 

 healthier, stronger, and better nourished body, due to lessened waste 



^1 Some tribes, when hungry or starving, partly evade or decei\-e this tactile 

 sensitiveness and repugnance by filling their empty stomachs with a fine clay, or a 

 fine, flour-like powder composed of exceedingly minute shells. 



