o2 Elliot, Inheritance of Acquired Characters. [ Januaiy 



one species should inhabit various islands, between which are 

 others containing distinct forms of the same genus. This may 

 be accounted for in two ways. First, a species may have been 

 widely dispersed over the continent ; and when portions of this 

 had disappeared beneath the waves, the fragments that remained 

 above water at the outset were all inhabited by the same species ; 

 but the physical and other conditions of the environment at inter- 

 mediate points were of a diflerent character from those at the 

 extremes, and in course of time the individuals, influenced by 

 their environment, isolated on intervening islands, departed from 

 their types, while others, though widely separated, retained their 

 characters. Or, second, it may have been, on the breaking up 

 of the continent, a portion of this inhabited by a strictly local 

 form, but one surrounded by a more widely disseminated and 

 typical species had not been submerged. This might explain 

 the fact of why a distinct form should intrude itself on an island 

 lying between others inhabited by a different one, the species 

 with the greater range having been preserved at the extremes of 

 its habitat which also had become islands. Thus isolation and 

 environment had fulfilled their work, but the form remained true 

 to its type, except where the environment had been changed.* 



Other groups in the same genus present similar gradations of 

 change and typical departures, but the above is sufficient for the 

 present illustration. Now what has caused this variation.^ If, 

 as we may suppose would be asserted by Weismann and his fol- 

 lowers, it has occurred through natural selection and not by the 

 parent transmitting its acquired characters to its offspring, how 

 did the principle named act, if the environment was not sufficient 

 to influence the change.^ Weismann acknowledges that the 

 g-erfti-plasm^ that is, what he designates as the vmdying part of 

 the organism contained in the germ-cells, may itself be modified 

 through the action of the environment on the soina^ that is, the 

 body, increasing its nutrition, yet he denies that definite changes 

 induced in certain parts of the soma by the action of the environ- 

 ment can be transmitted to a suceeeding genei"ation. If, as 

 granted by Weismann, the so-called 'immortal' part of the or- 

 ganism can be changed or modified by the influences of the en- 

 vironment, is it not reasonable to suppose that such modifications 



*In this connection see Baur, 'Origin of the Galapagos Islands,' Am. Nat. iSgi^p. 107. 



