about what he considered his natural clumsiness, and expressed a fear that he should never be able to make satisfactory microscopic sections; as to his being able to make drawings of his dissections and microscopical preparations, he looked upon that at first as wholly impossible. I need hardly say that in time he acquired great skill in the details of microscopical technique, and that his drawings, if wanting in so-called artistic finish, were always singularly true and instructive. While thus struggling with the details which I could teach him, he soon began to manifest qualities which no teacher could give him. I remember calling his attention to Dursy's paper on the Primitive Streak, and suggesting that he should work the matter over, since if such a structure really existed, it must, most probably, have great morphological significance. I am free to confess that I myself rather doubted the matter, and a weaker student might have been influenced by my preconceptions. Balfour, however, thus early had the power of seeing what existed and of refusing to see what did not exist. He was soon able to convince me that Dursy's streak was a reality, and the complete working out of its significance occupied his thoughts to the end of his days.

The results of these early studies were made known in three papers which appeared in the Quarterly Journal of Microscopical Science for July 1873, and will be found in the beginning of this volume. The summer and autumn of that year were spent partly in a visit to Finland, in company with his friend and old school-fellow Mr Arthur Evans, and partly in formal preparation for the approaching Tripos examination. Into this preparation Balfour threw himself with characteristic energy, and fully justified my having encouraged his spending so much of the preceding time in original research, not only by the rapidity with which he accumulated the stock of knowledge of various kinds necessary for the examination but also by the manner in which he acquitted himself at the trial itself. At that time the position of the candidates in the Natural Sciences Tripos was determined by the total number of marks, and Balfour was placed second, the first place being gained by H. Newell Martin of Christ's College, now Professor at Baltimore, U.S.A. In the examination, in which I took part, Balfour did not write much, and he had not yet learnt the art of putting his statements in the best 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 interest 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 phenomena 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 examination was concluded it was found that in his written answers he had not been very successful; he had not even acquitted himself so well as in the Tripos of the year before, and had the election been determined by the results of the examination alone, the examiners would have been led to choose the gentleman who was Balfour's only competitor. The original work however which Balfour sent in, including a preliminary account of the discoveries made at Naples, was obviously of so high a merit and was spoken of in such enthusiastic terms by the External Referee Prof. Huxley, that the examiners did not hesitate for a moment to neglect altogether the formal written answers (and indeed the papers of questions were only introduced as a safeguard, or as a resource in case evidence of original power should be wanted) and unanimously recommended him for election. Accordingly he was elected Fellow in the early days of October.

Almost immediately after, the little book on Embryology appeared, on which he and I had been at work, he doing his share even while his hands and mind were full of the Elasmobranch inquiry. The title-page was kept back some little time in order that his name might appear on it with the addition of Fellow of Trinity, a title of which he was then, and indeed always continued to be, proud. He also published in the October number of the Quarterly Journal of Microscopical Science a preliminary account of his Elasmobranch researches.

He and his friends thought that after these almost incessant labours, and the excitement necessarily contingent upon the fellowship election, he needed rest and change. Accordingly on the 17th of October he started with his friend Marlborough Pryor on a voyage to the west coast of South America. They travelled thither by the Isthmus of Panama, visited Peru and Chili, and returned home along the usual route by the Horn; reaching England some time in Feb. 1875.

Refreshed by this holiday, he now felt anxious to complete as far as possible his Elasmobranch work, and very soon after his return home, in fact in March, made his way again to Naples, where he remained till the hot weather set in in May. On his return to Cambridge, he still continued working on the Elasmobranchii, receiving material partly from Naples, partly from the Brighton Aquarium, the then director of which, Mr Henry Lee, spared no pains to provide him both with embryo and adult fishes. While at Naples, he communicated to the Philosophical Society at Cambridge a remarkable paper on The Early Stages of Vertebrates, which was published in full in the Quarterly Journal of Microscopical Science, July, 1875; he also sent me a paper on The Development of the Spinal Nerves, which I communicated to the Royal Society, and which was subsequently published in the Philosophical Transactions of 1876. He further wrote in the course of the summer and published in the Journal of Anatomy and Physiology in