468 THE WONDER OF LIFE 



We are familiar with this in some lower animals, such as 

 May-flies and butterflies, and in some still lower animals, 

 such as some of the worms, but it is rather startling to find 

 a big muscular sea lamprey a yard long and as thick as a 

 lady's wrist dead and stranded in the shallow water of 

 the river not far below the spawning-place. What does 

 it all mean ? Uprooting and transporting the stones has 

 involved no small expenditure of energy, no little wear and 

 tear ; the skin is often bruised and cut (and there are 

 wounds of combat and of mating besides) ; Bacteria and 

 Fungi begin to settle down (to which the skin of the larva 

 seems to be immune because of a ferment it possesses) ; 

 the creatures become blind and emaciated, and are often 

 attacked by other lampreys. But all the external causes 

 added up will not account for the wiping out of the adult 

 lampreys after spawning. Every one agrees that these 

 are contributory or accessory, but not the essential causes 

 of death. 



A deeper answer is to be found in the fundamental 

 antithesis between nutrition and reproduction. These 

 sexually mature lampreys have not been feeding at all : 

 their hunger has been devoured by love. Profound bodily 

 changes have been associated with the reproductive func- 

 tion, similar to those more familiar in the case of the salmon. 

 The intestine, for instance, is quite out of gear. Deeper still, 

 perhaps, it is possible to go, for it seems legitimate to 

 suppose that the length of life's tether is, in many cases at 

 least, adaptive. Where reproduction takes such a grip 

 of the constitution, it would not be well for the race that 

 there should be survival. In other words, those of a type 

 that tended to live longer, but with enfeebled energies, 

 have been eliminated in the course of Natural Selection. 



