THE REPRODUCTIVE FACTOR IN EVOLUTION. 313 



entire theory of organic evolution. Leaving this to other 

 papers, but specially to a future work, suffice it here, in con- 

 clusion, to indicate an important change in the general point of 

 view. The older biologists have been primarily anatomists, 

 analysing and comparing the form of the organism, separate 

 and dead ; however incompletely, we have sought rather to be 

 physiologists, studying and interpreting the highest and intensest 

 activity of things living. From the study of individual structure 

 they were wont to pass, indeed, to that of reproductive 

 structures, and thence even functions ; hence, too, the pair 

 and the totality of the species did at length come successively 

 into view ; but this with the individualistic theory of natural 

 selection bulking as practically all-important in the foreground, 

 to which even sexual selection was a mere harmonious corollary. 

 For us, however, this perspective has become entirely reversed. 

 The individual is a mere link in the species, and its repro- 

 ductive processes are thus of fundamental importance to the 

 interpretation even of its self-maintaining ones. Hence we no 

 longer regard, with Darwin and the majority of our brother 

 naturalists, the operation of natural selection upon individual 

 characters as the simplest of problems, looking for residual 

 explanation to sexual selection, and only in extreme difficulty 

 invoking the aid of " principles of correlation," " laws of 

 growth," and the like, viewed as almost inscrutably mysterious. 

 On the contrary, it is the continual correlation yet antithesis — 

 the action and reaction — of vegetative and reproductive pro- 

 cesses in alternate preponderance, which seems to us of 

 fundamental importance, since to this the general rhythm of 

 individual and racial life runs fully parallel. Hence it is that 

 we have the primeval lily developing on the one hand the 

 ideally vegetative grass, yet also the supremely specialised re- 

 productive orchid ; and that we can trace (as we hold) the same 

 swing of divergent evolution, of definite variation, in every 

 natural order, nay, in every genus, often even in the very 

 varieties of a species. Hence, too, it is that the rhythm of hydroid 

 and medusoid in the individual life of the typical forms becomes 

 fixed in coral or ctenophore as a racial temperament. This 

 preponderance of passivity or activity (which we can read 

 throughout, in barnacle and insect, as well as in tortoise and 

 swallow) once set up, goes on accumulating till it meets rever- 

 sal through environment or other causes, and limitation or 

 extinction through the agency of natural selection, which, 



