68 Scientific Proceedings, Royal Dublin Society. 



Progressive Activity and Sex. 



We saw in the case of the cell how the organism got into 

 " Physiological difficulties " ^ after it had attained to certain 

 dimensions. It was evident that, in order to best fulfil a law of 

 accelerated activity, some new departure in life-history was then 

 required. This was taken in reproduction, and it appeared as if 

 the organism had two ways of meeting the environment according 

 as the conditions favoured anabolism or katabolism. That these, 

 throughout nature, sum up the characteristics of maleness and 

 femaleness, has been urged by Professors Greddes and Thomson 

 ("Evolution of Sex"). From the present point of view, both are 

 primarily methods for responding to the stimulus of energy in a 

 progressive manner, and each of these is that best calculated to do 

 so under the conditions which call it forth. Rest, assimilation, and 

 large reproductive sacrifice in the case of the rich medium. Active 

 exploration, involved in the reproduction of smaller and more 

 numerous units, in the case of the poor medium. 



Thus, the often wingless female aphid, in the abundance of 

 spring and early summer, hourly carries on a parthenogenetic 

 and viviparous reproduction ; but in the poorer time of autumn the 

 winged male aphid makes his appearance, and the less costly but 

 more numerous oviparous sexual reproduction commences. The 

 same order of nature is brought to view in Yung's experiments on 

 tadpoles : i.e. that starvation favours maleness, abundance female- 

 ness.^ Sometimes the activity of the male is utilised in bringing 

 supplies to the more vegetative female. In the case of birds, the 

 energies of the female are thus expended on the production of 

 the necessary amount of warmth for incubation, the male bird very 

 generally feeding her upon the nest. 



In short, reproduction may be regarded as one phase of obe- 

 dience to the law of progress. It has been defined as " discontinuous 

 growth." So that, philosophically, we view the entire succession 

 as one organic whole. And we consider the organism as following 



1 "The Evolution of Sex," Geddes and Thomson, p. 220. 



2 Ibid., chap. iv. A lemarkable instance of the action of these laws is given on 

 p 235, in the case of a ciliated infusorian. 



