THE FACTORS OF ORGANIC EVOLUTION. 23 



obstacle to the circulation offered by some important 

 structure in a diseased or disordered state, throwing more 

 strain upon the heart, causes hypertrophy of its muscular 

 walls; and this change which is, so far as concerns the 

 primary evil, a remedial one, often entails mischiefs in 

 other organs. &quot;Apoplexy and palsy, in a scarcely credible 

 number of cases, are directly dependent on hypertropic 

 enlargement of the heart.&quot; And in other cases, asthma, 

 dropsy, and epilepsy are caused. Now if a result of this 

 inter-dependence as seen in the individual organism, is that 

 a local modification of one part produces, by changing their 

 functions, correlative modifications of other parts, then the 

 question here to be put is Are these correlative modifica 

 tions, when of a kind falling within normal limits, inheritable 

 or not. If they are inheritable, then the fact stated by Mr. 

 Darwin that &quot; when one part is modified through continued 

 selection,&quot; &quot; other parts of the organization will be una 

 voidably modified&quot; is perfectly intelligible : these entailed 

 secondary modifications are transmitted pari passu with the 

 successive modifications produced by selection. But what if 

 they are not inheritable ? Then these secondary modifications 

 caused in the individual, not being transmitted to descend 

 ants, the descendants must commence life with organiza 

 tions out of balance, and with each increment of change 

 in the part affected by selection, their organizations must 

 get more out of balance must have a larger and larger 

 amounts of re-organization to be made during their lives. 

 Hence the constitution of the variety must become more 

 and more unworkable. 



The only imaginable alternative is that the re-adjust- 

 ments are effected in course of time by natural selection. 

 But, in the first place, as we find no proof of concomitant 

 variation among directly co-operative parts which are 

 closely united, there cannot be assumed any concomitant 

 variation among parts which are both indirectly co-opera 

 tive and far from one another. And, in the second place, 



