210 THE EVOLUTION OF SEX. 



further up still, where nutrition is relatively less active and katabolism 

 is maximized, the formation of flowers indicates the appearance of 

 sexual reproduction. 



In many ferns, the contrast between the vegetative and reproduc- 

 tive regions of the organism is as marked as in the flowering plant. 

 Thus the moon wort {Botrychmm) and the adder's tongue {Ophioglos- 

 sum) have their spore-bearing shoots standing in conspicuous antithesis 

 to the leafy portion, and a similar contrast is well seen in the royal 

 fern (Osmunda) and some of its allies. 



In animals, the contrast in position between reproductive organs 

 and the general body is never so marked. Yet the generally posterior 

 position of the organs, their frequent close association with the excre- 

 tory system, their occasional rupture as external sacs, must not be 

 lost sight of. 



(6) The Contrast in the Individual Life. — Growth during youth, 

 sexual maturity at the limit of growth, the continued alternation of 

 vegetative and reproductive periods, are common-places of observation 

 which require no emphasis. If growth and vegetative increase are 

 the outcome of preponderant anabolism, reproduction and sexuality as 

 their antitheses must represent the katabolic reaction from these. But 

 anabolism and katabolism are the two sides of protoplasmic life ; and 

 the major rhythms of their respective preponderance of these, give the 

 familiar antitheses we have been noting. These contrasts of metabol- 

 ism represent the swings of the organic see-saw; the periodic contrasts 

 correspond to alternate weightings or lightenings of the two sides. 

 Yet the contrast is less than it seems. In previous chapters we have 

 seen how growth, becoming overgrowth, turns into reproduction ; and 

 how sexual reproduction, dispensing with fertilization, may degenerate 

 till we know it no longer from growth. Reproduction, moreover, is 

 as primitive as nutrition, for not only do hunger and love become 

 indistinguishable in that equal-sided conjugation which has been curi- 

 ously called "isophagy," but nutrition in turn is nothing more than 

 continual reproduction of the protoplasm. Here, indeed, we have 

 been anticipated by Hatschek, who clearly states the more than verbal 

 paradox, that all nutrition is reproduction. 



VII. The Contrast between Asexual and Sexual Repro- 

 duction. — In plenty, the hydra buds; in poverty, it reproduces 

 sexually. In the same way, the liverwort on the flower-pot bears its 

 pretty cryptogamic " flowers " when its exuberant growth and bud- 

 ding have come to an end. On rich soil the plant has luxuriant 

 foliage ; but great abundance is the reverse of conducive to the richest 

 crop of flowers and fruit. Gruber, Maupas, and others, have shown 

 that abundant nutrition favors the asexual multiplication, that is, the 



