Conclusion 



IN the foregoing chapters some attempt 

 has been made to review the multi- 

 tudinous life of the water world and to 

 give some idea of the interdependence of 

 the various groups. Life from small be- 

 ginnings has tended and still tends to 

 develop more and more complex forms 

 which in turn rely for their continued 

 existence upon other forms lower in the 

 scale. The leviathan that ploughs the 

 ocean and the water flea that populates 

 the stagnant ditch are not mere isolated 

 phenomena, but integral parts of a vast 

 harmonious whole. But one is led to 

 ask " What of the future ? " 



All the evidence to-day points to the 

 present age as being the hey-day of the 

 mammals. No giant shark or reptile of 

 253 



