V] OF FORM AND SPECIES 251 



the element of time, and of succession, or discuss their origin and 

 affihation as an historical sequence of events. But in biology, the 

 term species carries with it many large, though often vague 

 assumptions. Though the doctrine or concept of the " permanence 

 of species" is dead and gone, yet a certain definite value, or sort 

 of quasi-permanency, is still connoted by the term. Thus if a tiny 

 foraminiferal shell, a Lagena for instance, be found living to-day, 

 and a shell indistinguishable from it to the eye be found fossil 

 in the Chalk or some other remote geological formation, the 

 assumption is deemed legitimate that that species has "survived," 

 and has handed down its minute specific character or characters, 

 from generation to generation, unchanged for untold n\yriads of 

 vears*. Or if the ancient forms be like to, rather than identical 

 with the recent, we still assume an unbroken descent, accompanied 

 by the hereditary transmission of common characters and pro- 

 gressive variations. And if two identical forms be discovered at 

 the ends of the earth, still (with occasional slight reservations on 

 the score of possible "homoplasy"), we build hypotheses on this 

 fact of identity, taking it for granted that the two appertain to 

 a common stock, whose dispersal in space must somehow be 

 accounted for, its route traced, its epoch determined, and its 

 causes discussed or discovered. In short, the naturalist admits 

 no exception to the rule that a "natural classification" can only 

 be a genealogical one, nor ever doubts that " The fact that we are 

 able to classify organisms at all in accordance with the structural 

 characteristics ivhich they fresent, is due to the fact of their being 

 related by descenti" But this great generahsation is apt in my 

 opinion, to carry us too far. It may be safe and sure and helpful 

 and illuminating when we apply it to such complex entities, — 

 such thousand-fold resultants of the combination and permutation 

 of many variable characters,^ — as a horse, a lion or an eagle ; 

 but (to my mind) it has a very different look, and a far less firm 

 foundation, when we attempt to extend it to minute organisms 

 whose specific characters are few and simple, whose simplicity 



* Cf. Bergson, Creative Evolution, p. 107: "Certain Foraminifera have not 

 varied since the Sihirian epoch. Unmoved witnesses of the innumerable revolu- 

 tions that have upheaved our planet, the Lingulae are today what they were at 

 the remotest times of the palaeozoic era." 



t Ray Lankester, A.M.N.H. (4), xi, p. .321, 1873. 



