186 Degeneratio7i in the Ostrich 



The slow, continuous, determinate nature of the changes going on 

 in so many directions in the ostrich is altogether in harmony with the 

 conception of a gradual advent of senility. Somatic cells, as becomes 

 their temporary, individual character, are all too rapid in their approach 

 to old age ; whereas germ cells, as becomes their racial significance and 

 value, approach decadence with extreme slowness. If we countenance 

 germinal senility in the ostrich it is however as a senility of the indi- 

 vidual factorial constituents of the germ plasm, not of the germ as a 

 whole; the factorial conception of the nature of the organisms would 

 lead us to expect this, though the latter might easily be contemplated. 

 Were any support needed for the hypothesis of genetic factors, the inde- 

 pendence of the various retrogressive changes in the ostrich would of 

 itself be most convincing. 



It would be an attractive reflection if, in such a case as the ostrich, 

 we could establish that in a general way the order of retrogressive evolu- 

 tion is the reverse of that of progressive evolution. Feathers, scales and 

 claws are indeed recent phylar acquisitions, and the essential vertebrate 

 structures were laid down long before digitate limbs came into being. 



On the above conception of the germ plasm of the ostrich as under- 

 going regular successional changes in various directions, perhaps of the 

 nature of fractionation and loss, it is implied that the changes are in 

 progress among the individuals of the race as a whole ; in other words, 

 that the ostrich race presents us with an example of mass mutation. 

 The degradation tendencies within the germ plasm being the same 

 throughout, the changes appear independently in the individual members 

 of the race. In his Presidential Address before the British Association 

 in Australia in 1914 Prof Bateson expresses himself in the strongest 

 terms against a view of this nature : " Modern research lends not 

 the smallest encouragement or sanction to the view that gradual evolu- 

 tion occurs by the transformation of masses of individuals, though 

 that fancy has fixed itself on popular imagination." It needs however 

 to be borne in mind that in the case of the ostrich we are in a position 

 to observe the changes in representatives from an area continental in its 

 extent, that certain specific characters show there has been no recent 

 intermingling between the members towards the extremes of the area, 

 that the changes are wholly intrinsic and of no appreciable selection 

 value, and that similar retrogressive mutations occur throughout, differing 

 only in the smaller details of the stages reached. The main facts are of 

 an altogether different order from those hitherto specially studied by 

 Mendelians, and may well be expected to influence our views accordingly. 



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