88 Scientific Proceedings, Royal Dublin Society. 



The Abundance and Activity of Life. 



We began by seeking in various manifestations of life a dyna- 

 mic principle sufficiently comprehensive to embrace the very various 

 phenomena. This, to all appearance, found, we have been led to 

 regard life, to a great extent, as a periodic dynamic phenomenon. 

 Fundamentally, in that characteristic of the contrivance, which 

 leads it to respond favourably to transfer of energy, its enormous 

 extension is due. It is probable that to its instability its numerical 

 abundance is to be traced — for this, necessitating the continual 

 supply of all the parts already formed, renders large, undifferen- 

 tiated growth, incompatible with the retardative laws of matter. 

 These are fundamental conditions of abundant life upon the 

 earth. 



Although we recognise in the instability of living systems the 

 underlying reason for their numerical abundance, secondary evolu- 

 tionary causes are at work. The most important of these is the 

 self-favouring nature of the phenomenon of reproduction. Thus 

 (" The Duration of Life "), there is a tendency not only to favour 

 reproductiveness, but early reproductiveness, in the form of one 

 prolific reproductive act, after which the individual dies. Hence 

 the wave-length of the species diminishes, reproduction is more 

 frequent, and correspondingly greater numbers come and go in 

 an interval of time. 



Another cause of the numerical abundance of life exists in the 

 conditions of nourishment already alluded to. Energy is more 

 readily conveyed to the various parts of the smaller mass, and hence 

 where supplies are abundant, the lesser organisms will more actively 

 functionate ; and this, as being the urging dynamic attitude, as well 

 as that most favourable in the struggle, will multiply and favour 

 such forms of life. On the other hand, however, these forms will 

 have less resource within themselves, and less power of endurance, 

 so that they are only suitable to fairly uniform conditions of 

 supply ; they cannot survive the long continued want of winter, 

 and so we have the seasonal abundance of summer. Only the 

 larger and more resistant organisms, whether animal or vegetable, 

 will, in general, populate the earth from year to year. From this 

 we may conclude that, but for the seasonal energy-tides, the develop- 

 ment of life upon the globe had gone along very different lines 



