620 APPENDIX G. 



of a plant, even so small as a scale, a complete plant may aris 

 necessitates it. And it is necessitated by the fact that among 

 plants, roots are produced by imbedded shoots and shoots by 

 roots, as well as by the fact that low animals, such as hydroids, 

 if deprived of both head and root, will develop a head from the 

 root part and a root from the head part, if their respective con- 

 ditions are inverted. All this evidence shows conclusively that 

 the component units of each species, whether existing in the germ 

 or in the developed organism, are, when not yet differentiated by 

 local conditions, all alike, and that the notion of special parts of 

 the germ-plasm correlated with special parts of the resulting or- 

 ganism, is entirely alien to the hypothesis. 



" But how do the units of a modified organ affect the units of 

 the germ in such wise that these produce an inherited modifica- 

 tion of the organ ? " will be asked. This difficulty has been dealt 

 with in §§ 97 d, 97 e, where the analogy between the social organism 

 and the individual organism has been brought in aid : serving, if 

 not to furnish a conception, yet to furnish an adumbration. Re- 

 garding citizens as the units of an unfolding society, say a colony, 

 it was pointed out that the nature they inherit from a mother- 

 society gives them a proclivity towards a society of like struc- 

 ture, the traits of which are progressively assumed as the 

 colony grows sufficiently large to make them possible. At the 

 same time it was pointed out that while the influence of the 

 entire aggregate on the individuals is seen in this forming of 

 them into a society of the inherited type, the influences of local 

 circumstances, and of individuals on one another, in each group, 

 make them differentiate into appropriate social structures, taking 

 on fit occupations and industries : the implication being that in 

 virtue of their inherited natures they all have partial capacities 

 for the various activities they undertake ; so that an immigrant 

 clerk sets up a tavern, a compositor takes to carpentering, and a 

 university man rides after cattle or is employed on a sheep farm. 

 Evidence was given in that place, as in the above paragraph, that 

 the constitutional units of an organism similarly have all of them 

 potentialities for taking on this or that structure and mode of 

 action which local conditions determine. It was further argued 

 that as citizens are continually being remoulded by their society 

 into congruity with it, and, if circumstances change them, tend to 

 remould their society ; so in the individual organism, there is this 

 reciprocal action of the whole on the units and of the units on 

 the whole. Hence it was inferred that the modified units in any 

 modified part tend to diffuse modifications like their own through 

 the units at large : being aided by the circulation of protoplasm, 

 as suggested in §§ 54c? and 97/. And it was urged that, however 

 inconceivably complex such a process may be, yet it seems not 



