342 Appendix A 



II. PROFESSOR C. LLOYD MORGAN 



[Extract from Habit and Instinct (1896), pp. 312 ff., previously printed by 

 request in Science, Nov. 20. 1896, pp. 793 ff., and delivered as one of a series 

 of ' Lowell Lectures ' in Boston, early in 1896.] 



" In his Romanes lecture, Professor Weismann makes another 

 suggestion which is valuable and may be further developed. 

 He is there dealing with what he terms ' intra-selection,' or 

 that which gives to the individual its plasticity. One of the 

 examples that he adduces is the structure of bone. ' Hermann 

 Meyer,' he says, 1 ' seems to have been the first to call attention 

 to the adaptiveness as regards minute structure in animal 

 tissues, which is most strikingly exhibited in the structure of the 

 spongy substance of the long bones in the higher vertebrates. 

 This substance is arranged on a similar mechanical principle 

 to that of arched structures in general ; it is composed of 

 numerous fine bony plates, so arranged as to withstand the 

 greatest amount of tension and pressure, and to give the utmost 

 firmness with a minimum expenditure of material. But the 

 direction, position, and strength of these bony plates are by 

 no means congenital or determined in advance ; they depend 

 on circumstances. If the bone is broken and heals out of the 

 straight, the plates of the spongy tissue become rearranged so 

 as to lie in a new direction of greatest tension and pressure ; 

 they can thus adapt themselves to changed circumstances.' 



" Then, after referring to the explanation by Wilhelm Roux 

 of the cause of these wonderfully fine adaptations, by applying 

 the principle of selection to the parts of the organism in which, 

 it is assumed, there is a struggle for existence among each 

 other, Professor Weismann proceeds to show 2 ' that it is not 

 the particular adaptive structures themselves that are trans- 

 mitted, but only the quality of the material from which intra- 

 selection forms these structures anew in each individual life. 

 ... It is not the particular spongy plates which are trans- 



1 Romanes Lecture on The Effect of External Influences on Development 

 (1894), pp. u, 12. 



2 Romanes Lecture, p. 15. 



