II36 LIFE : OUTLINES OF GENERAL BIOLOGY 



To make ourselves really at home in this method, it is useful actually 

 to take a plant and an animal specimen in either hand, and thus 

 to practise thinking of these as whole organisms, and yet also of their 

 organs, their tissues, their cells, and their protoplasm, as in suc- 

 cessive order of deepening analysis and understanding. 



Next as an example of how such a diagram is not only a definite 

 and orderly scheme of knowledge, but may be used as an actual 

 thinking-machine, suggestive towards acquiring more, we may here 

 cite our own theory of The Evolution of Sex (1889), which did 

 actually thus arise, and by help of this very diagram; as by working 

 our way upwards from the metabolism of living protoplasm and 

 to the respective preponderance of anabolism in ova, and of kata- 

 bolism in sperms, and thence following up this contrast, through 

 organs and their functioning, to their characteristically sex-distinct 

 individuals; and thence again through the corresponding dif- 

 ferentiations of taxonomic groupings, and their ecology also. 



An Addition to the Preceding Analysis, of Forms and 

 FuNCTiONiNGS. — Here, however, a further addition is useful. The 

 preceding descending analysis, both of forms and functions, from 

 individuals into organs, thence into tissues, and so on to cells and 

 protoplasm, is in use by aU biologists, as every manual shows. The 

 order in which the functions and organs are described may vary, 

 but the main animal functions are usually taken as digestion, 

 excretion, respiration, circulation, etc., and with reproduction 

 commonly mentioned last (or in elementary textbooks sometimes 

 not at all, as with Huxley's otherwise excellent and long paramount 

 Introduction). But here the botanist makes his contribution — not 

 simply by introducing another function, that characteristic of green 

 plants in light, as photosynthesis — but for the main distinction, so 

 familiar to all eyes, of the plant-life as in the first place manifested 

 in its root, stem, and leaves, as vegetative functionings and forms, 

 and thereafter, for usually much briefer period, advancing to its 

 reproductive life, with its flower, fruit, and seed. The forms and 

 functionings of the individual thus fall into two distinct Systems, 

 the vegetative and the reproductive, each paramount in its turn ; so 

 he is compelled to press this idea upon the student of animal and 

 human life, as no less fundamental also, however less conspicuous. 

 Our series thus in descending order once more is through individual 

 organism to (functional and morphological) systems, vegetative and 

 reproductive, for which the "functions" of the customary language 

 are rather to be called sub-functions, mostly common to both, 

 though in varied proportions. 



This introduction of a fresh bookshelf, below the initial one, is 

 important, since obvious in plant development, but manifested 

 throughout animal and human life as well. The importance of this 

 has of course been pointed out from many sides, as most notably 



