v.] SPECIFIC STABILITY. 127 



CHAPTER V. 



AS TO SrECIFIO STABILITY. 



Vkhnt Is moant by tho I'lirnso " Spodflc SUiWlity;" such 8tnl)illty to bo expected a 

 /)r/rt;7, «ir duo Consldcnililo Clmnpcs nt onco. — Knpldly-innvnsiiip Dldlciilty of iii- 

 tf^nslfyliifj IJa('<* ("Imrmtoif* ; Allct'i'il CftiiMfS of fliln IMn'Tiomcrioii ; probaMy an In- 

 ternal Cause rf)nperatcH. — A Cerlnlii l)e(lnltenos.H In Variations. — Mr. Darwin ad- 

 niltfl llie I'rlnclidn of Si.cclllr Slablllfy 111 C'erUIn <"aRe«of Unetpial VariabllKy.— 

 The <1oose. — The IVaoock. — The Onlnea-fowl. — Ivxropllonal Cansea of Variation 

 un<lor Doincstlration. — Alleged Tendency to llovcrslon. — Instnnces. — Sterility of 

 Hybrids. — PreiJotency of Pollen of same Species, biit of DilTercnt liaee. — Mortality 

 in Young flallinacoon.s Hybrids. — A Bar to Internilxtnro exists soinowhcro. — 

 Guinea-pigs. — Summary and Conclusion. 



As was observed in the preceding chapters, arguments 

 may yet be advanced in favor of the opinion that species 

 are stable (at least in the intervals of their comparatively 

 sudden successive manifestations) ; that the organic world 

 consists, according to Mr. Galton's before-mentioned con- 

 cej)<ion, of many faceted spheroids, each of which can re- 

 pose upon any one facet, but, when too much disturbed, 

 rolls over till it finds repose in stable equilibrium upon 

 another and distinct facet. Something, it is here con- 

 tended, may be urged, in favor of the existence of such 

 facets — of such intermitting conditions of stable equilib- 

 rium. 



A view as to the stability of species, in the intervals of 

 change, has been well expressed in an able article, before 

 quoted from, as follows : ' "A given animal or plant ajv 

 pears to be contained, as it were, within a s])here of varia- 



' Norfh British Review, New Series, vol, vii., March, 1867, p. 282. 



