164 SUMMARY. [Chap. VI, 



it will fulfil all the requirements of natural selection, though it may 

 cause the death of some few members. If we admire the truly- 

 wonderful power of scent by which the males of many insects find 

 their females, can we admire the production for this single purpose 

 of thousands of drones, which are utterly useless to the community 

 for any other purpose, and which are ultimately slaughtered by 

 their industrious and sterile sisters ? It may be difficult, but we 

 ought to admire the savage instinctive hatred of the queen-bee, 

 which urges her to destroy the young queens, her daughters, as soon 

 as they are born, or to perish herself in the combat ; for undoubtedly 

 this is for the good of the community ; and maternal love or ma- 

 ternal hatred, though the latter fortunately is most rare, is all the 

 same to the inexorable principle of natural selection. If we admire 

 the several ingenious contrivances, by which orchids and many other 

 plants are fertilised through insect agency, can we consider as 

 equally perfect the elaboration of dense clouds of pollen by our 

 fir-trees, so that a few granules may be wafted by chance on to the 

 ? 



Summary: the Laiv of Unity of Type and of the Conditions of 

 Existence embraced by the Theory of Natural Selection. 

 We have in this chapter discussed some of the difficulties and 

 objections which may be urged against the theory. Many of them 

 are serious ; but I think that in the discussion light has been thrown 

 on several facts, which on the belief of independent acts of creation 

 are utterly obscure. We have seen that species at any one period 

 are not indefinitely variable, and are not linked together by a 

 multitude of intermediate gradations, partly because the process of 

 natural selection is always very slow, and at any one time acts only 

 on a few forms; and partly because the veiy process of natural 

 selection implies the continual supplanting and extinction of pre- 

 ceding and intermediate gradations. Closely allied species, now 

 living on a continuous area, must often have been formed when the 

 area was not continuous, and when the conditions of life did not 

 insensibly graduate away from one part to another. When two 

 varieties are formed in two districts of a continuous area, an inter- 

 mediate variety will often be formed, fitted for an intermediate 

 zone ; but from reasons assigned, the intermediate variety will 

 usually exist in lesser numbers than the two forms which it 

 connects ; consequently the two latter, during the course of further 

 modification, from existing in greater numbers, will have a great 

 advantage over the less numerous intermediate variety, and will 

 thus generally succeed in supplanting and exterminating it. 



