INTRODUCTION. 



possible form ; he won his position chiefly by the firm thought 

 and clear insight which was present in almost all his answers. 



The examination was over in the early days of Dec. 1873 

 and Balfour was now free to devote himself wholly to his 

 original work. Happily, the University had not long before 

 secured the use of two of the tables at the then recently founded 

 Stazione Zoologica at Naples. And upon the nomination of the 

 University, Balfour, about Christmas, started for Naples in 

 company with his friend Mr A. G. Dew-Smith, also of Trinity 

 College. The latter was about to carry on some physiological 

 observations ; Balfour had set himself to work out as completely 

 as he could the embryology of Elasmobranch fishes, about which 

 little was at that time known, but which, from the striking 

 characters of the adult animals could not help proving of in- 

 terest and importance. 



From his arrival there at Christmas 1873 until he left in 

 June 1874, he worked assiduously, and with such success, that 

 as the result of the half-year's work he had made a whole series 

 of observations of the greatest importance. Of these perhaps 

 the most striking were those on the development of the urogenital 

 organs, on the neurenteric canal, on the development of the 

 spinal nerves, on the formation of the layers and on the phe- 

 nomena of segmentation, including a history of the behaviour 

 of nuclei in cell division. He returned home laden with facts 

 and views both novel and destined to influence largely the 

 progress of embryology. 



In August of the same year he attended the meeting of 

 the British Association for the Advancement of Science at 

 Belfast ; and the account he then gave of his researches formed 

 one of the most important incidents at the Biological Section 

 on that occasion. 



In the September of that year the triennial fellowship for 

 Natural Science was to be awarded at Trinity College, and 

 Balfour naturally was a candidate. The election was, according 

 to the regulations, to be determined partly by the result of an 

 examination in various branches of science, and partly by such 

 evidence of ability and promise as might be afforded by original 

 work, published or in manuscript. He spent the remainder of 

 the autumn in preparation for this examination. But when the 



