1922,] Ac(/>(ired or Somatic Variafinns. 71)5 



I would crave tlie indulgence of readers of 'The Ibis' 

 while I make an additional defence of my statement : for, 

 tired as the}" may be of the Bermuda Goldfinch, the principle 

 at stake is one, the importance of which can hardly be 

 exngoerated if we are to take any interest in the philoso- 

 phical side of Ornithology, and, more particularly, in the 

 suliject of Variations and the part tiiey play in Evolution. 

 The problem, simply stated, resolves itself into this — is 

 this character (the darker coloration which distinguishes 

 Bermudan from European Goldfinches) hereditarily inborn 

 or is it due to some somatic modification either "ante-natal " 

 or ^' post-natal " ? 



If the character is inherited, then it is inherited through 

 some controlling factor or gene which is represented in the 

 chromosomes of tb.e nuclei present in the germ-cells of tlie 

 parent birds. I have already stated that I cannot believe 

 this to be the case. 



On the other hand, the following explanation appears to 

 me to be the more likely solution of the problem ; at the 

 same time it might possibly solve Mr. Witherby's difficulty 

 in connection with the distinctive character appearing in the 

 first brood hatched on the island, or that which some orni- 

 thologists feel in accountiny,' for the fact that the chicks of 

 other similar variations in other species are hatched with 

 the variation already evident before external environmental 

 influences have bad time to operate. 



The fertilized ovum then, according to my contention, 

 contains no factor for a " darker coloration," but as it 

 passes along the oviduct it receives an enveloping layer or 

 mantle of albumen derived from maternal sources. It is 

 obvious that this maternal nurture, taken in conjunction 

 with the maternal blood-supply present in the follicular 

 stroma of the ovary, must play an imj)ortant part in the 

 development and vigour of the ovum. Tlie ovum is, in fact, 

 both before and after fertilization, surrounded by a somatic 

 maternal environment. If the vigour or the physio-chemical 

 tone of the ])aients has been intensified by a congenial 

 eJvternal environment such as the Bermudas, all the 



