34 PRESIDENTIAL ADDRESS SECTION D. 



his legs and hops away encumbered with them. Some weeks later 

 he visits the water and the eggs are hatched. The emerging tad- 

 poles have already covered up their gills. Kammerer provided 

 adult Alytes with a tank for bathing. They began to pair in the 

 water. Under this circumstance the eggs slipped off the male's 

 legs and remained in the water. Only a few of them survived. 

 But the toads hatched from these eggs paired in the water. The 

 females laid smaller eggs and the tadpoles from them had external 

 gills, but only one on each side. However, the third generation of 

 Alytes raised in the water produced eggs that gave rise to tadpoles 

 with three external gills on each side as in ordinary toads, while 

 the males had horny patches on their hands. By further experi- 

 ments it was found that the horny pad increased in size and de- 

 finiteness up to the fifth generation. Bateson has questioned some 

 of Kammerer's work. 



Further interesting experiments noted by MacBride are those 

 of Guyer and Smith, published in 1920. These observers worked 

 on rabbits. The lenses of the eyes of rabbits were pulped in 

 Ringer's solution, and the fluid injected into domestic fowls. After 

 a few weeks an antibody developed in the fowl's blood. Fowl 

 serum containing the antibody was injected into pregnant rabbits. 

 The mothers were unaffected, but some of the young showed 

 diminished or aborted lenses to their eyes, and correspondingly 

 developed retinae. Many of the young with imperfect eyes died, 

 but some survived. These mated together gave rise to young, 

 some of which showed the defect, and this defect was observable 

 through six generations without any further injection of serum. 

 Two instances of inheritance through the male alone were noted. 

 The defects once established became more pronounced in successive 

 generations. Guyer and Smith suggest that "the degenerating 

 eyes are themselves directly or indirectly originating antibodies in 

 the blood serum of their bearers — which in turn affect the germ 

 .cells." 



We have now briefly reviewed some of the modern ideas on 

 the processes or modes of evolution. In the past too much appears 

 to have been made of differences between the various hypotheses put 

 forward to explain the processes. Ruggles Gates has suggested that 

 the higher organisms exhibit two types of characters, namely, cell 

 characters arising as mutations, and organismal characters (en- 

 vironmental or orthogenic) which may modify localised parts of 

 the life cvcle. We have seen how the views of Jennings and Castle 

 indicate the merging of mutations and continuous variations. Pos- 

 sibly through the agency or interaction of internal secretions or 

 chemical messengers, as yet perhaps not fully understood, the 

 various discrepancies in the hypotheses may be reconciled and their 

 inter-rel ationships demonstrated . 



Application to Present-Day Problems. 



The outstanding features all over the world to-day are the 



struggle between nations closely linked with the struggle between 



Capital and Labour. Statesmen are powerless, leaders are not 



obeyed. Moderate opinion is swamped by extremes and exaggera- 



