Section D. 



BIOLOGY. 



ADDRESS BY THE PRESIDENT : 



PROFESSOR H. B. KIRK. M.A., 



Professor of Biology in Victoria College, Wellington, N,Z. 



THE PRESENT ASPECT OF SOME PROBLEMS OF HEREDITY. 



The subject of heredity is one in which all biologists must always 

 take the keenest interest, in view of its far-reaching and fundamental 

 importance. We must recognise that there centre in it all the questions 

 of variation, whether of advancing or of retrogressive evolution, for it 

 is the nexus that links into a continuous existence the series of genera- 

 tions that the limitations of custom often lead us to regard as so 

 many discontinuities. The methods of heredity then and the laws that 

 govern those methods become more and more the field of exact 

 experiment and study. Thus we are brought to review periodically 

 the fresh advance of actual knowledge in this field, and to see, as far as 

 may be, what conclusions are possible or towards what conclusions 

 we are tending. 



Of the many problems of heredity, I shall in this address refer to 

 only two — the problem of Amphimixis, in so far as it is illuminated by 

 virgin generation artificially induced, and the problem of the Inheri- 

 tance of Acquired Characters, thorniest, perhaps, of all questions 

 connected with Evolution. I shall also, if your patience holds, refer 

 at no great length to Mnemic Theories of Heredity. 



Artificial Parthenogenesis. 



All are familiar with the fact that parthenogenesis (virgin genera- 

 tion) forms naturally part of the life cycle of many animals and plants, 

 often taking place for several generations in succession, and alternating 

 with sexual generation. Many are well acquainted with the fact that 

 parthenogenesis can, in many organisms, be artificially induced ; for 

 example, that it can be induced by applying mechanical stimuli to the 

 eggs of some of those insects in which it does not ordinarily occur. In 

 Echinoderms parthenogenesis has been induced with great success. 

 It has long been known that mechanical stimuli would induce the 

 unferbilized egg of the frog to go through the earlier stages of segmenta- 

 tion. As such a phenomenon in a Vertebrate animal challenges interest, 

 it is not surprising that the older experiments with the frog's egg have 

 never been lost sight of ; and latterly very striking results have been 

 achieved, in which French workers of the school of Delage have led the 

 way. 



