The years at Harrow passed quickly away, Balfour making fair, but perhaps not more than fair, progress in the ordinary school learning. In due course however he reached the upper sixth form, and in his last year, became a monitor. At the same time his exact scientific knowledge was rapidly increasing. Geology still continued to be his favorite study, and in this he made no mean progress. During his last years at Harrow he and his brother Gerald worked out together some views concerning the geology of their native county. These views they ultimately embodied in a paper, which was published in their joint names in the Geological Magazine for 1872, under the title of “Some Points in the Geology of the East Lothian Coast,” and which was in itself a work of considerable promise. Geology however was beginning to find a rival in natural history. Much of his holiday time was now spent in dredging for marine animals along the coast off Dunbar. Each specimen thus obtained was carefully determined and exact records were kept of the various 'finds,' so that the dredgings (which were zealously continued after he had left Harrow and gone to Cambridge) really constituted a serious study of the fauna of this part of the coast. They also enabled him to make a not inconsiderable collection of shells, in the arrangement of which he was assisted by his sister Evelyn, of crustacea and of other animals.
Both to the masters and to his schoolfellows he became known as a boy of great force of character. Among the latter his scrupulous and unwavering conscientiousness made him less popular perhaps than might have been expected from his bright kindly manner and his unselfish warmheartedness. In the incidents of school life a too strict conscience is often an inconvenience, and the sternness and energy with which Balfour denounced acts of meanness and falsehood were thought by some to be unnecessarily great. He thus came to be feared rather than liked by many, and comparatively few grew to be sufficiently intimate with him to appreciate the warmth of his affections and the charm of his playful moments.
At the Easter of 1870 he passed the entrance examination at Trinity College, Cambridge, and entered into residence in the following October. His college tutor was Mr J. Prior, but he was from the first assisted and guided in his studies by his friend, Mr Marlborough Pryor, an old Harrow boy, who in the same October had been, on account of his distinction in Natural Science, elected a Fellow of the College, in accordance with certain new regulations which then came into action for the first time, and which provided that every three years one of the College Fellowships should be awarded for excellence in some branch or branches of Natural Science, as distinguished from mathematics, pure or mixed. During the whole of that year and part of the next Mr Marlborough Pryor remained in residence, and his influence in wisely directing Balfour's studies had a most beneficial effect on the latter's progress.
During his first term Balfour was occupied in preparation for the Previous Examination; and this he successfully passed at Christmas. After that he devoted himself entirely to Natural Science, attending lectures on several branches. During the Lent term he was a very diligent hearer of the lectures on Physiology which I was then giving as Trinity Prælector, having been appointed to that post in the same October that Balfour came into residence. At this time he was not very strong, and I remember very well noticing among my scanty audience, a pale retiring student, whose mind seemed at times divided between a desire to hear the lecture and a feeling that his frequent coughing was growing an annoyance to myself and the class. This delicate-looking student, I soon learnt, was named Balfour, and when the Rev. Coutts Trotter, Mr Pryor and myself came to examine the candidates for the Natural Science Scholarships which were awarded at Easter, we had no difficulty in giving the first place to him. In point of knowledge, and especially in the thoughtfulness and exactitude displayed in his papers and work, he was very clearly ahead of his competitors.
During the succeeding Easter term and the following winter he appears to have studied physics, chemistry, geology and comparative anatomy, both under Mr Marlborough Pryor and by means of lectures. He also continued to attend my lectures, but though I gradually got to know him more and more we did not become intimate until the Lent term of 1872. He had been very much interested in some lectures on embryology which I had given, and, since Marlborough Pryor had left or was about to leave Cambridge, he soon began to consult me a good deal about his studies. He commenced practical histological and embryological work under me, and I remember very vividly that one day when we were making a little excursion in search of nests and eggs of the stickleback in order that he might study the embryology of fishes, he definitely asked my opinion as to whether he might take up a scientific career with a fair chance of success. I had by this time formed a very high opinion of his abilities, and learning then for the first time that he had an income independent of his own exertions, my answer was very decidedly a positive one. Soon after, feeling more and more impressed with his power and increasingly satisfied both with his progress in biological studies and his sound general knowledge of other sciences, anxious also, it may be, at the same time that as much original inquiry as possible should be carried on at Cambridge in my department, I either suggested to him or acquiesced in his own suggestion that he should at once set to work on some distinct research; and as far as I remember the task which I first proposed to him was an investigation of the layers of the blastoderm in the chick. It must have been about the same time that I proposed to him to join me in preparing for publication a small work on Embryology, the materials for this I had ready to hand in a rough form as lectures which I had previously given. To this proposal he enthusiastically assented, and while the lighter task of writing what was to be written fell to me, he undertook to work over as far as was possible the many undetermined points and unsatisfactory statements across which we were continually coming.
During his two years at College his health had improved; though still hardly robust and always in danger of overworking himself, he obviously grew stronger. He rejoiced exceedingly in his work, never tiring of it, and was also making his worth felt among his fellow students, and especially perhaps among those of his own college whose studies did not lie in the same direction as his own. At this time he must have been altogether happy, but a sorrow now came upon him. His mother, to whom he was passionately attached, and to whose judicious care in his early days not only the right development of his strong character but even his scientific leanings were due, had for some time past been failing in health, though her condition caused no immediate alarm. In May 1872, however, she died quite suddenly from unsuspected heart disease. Her loss was a great blow to him, and for some time afterward I feared his health would give way; but he bore his grief quietly and manfully and threw himself with even increased vigour into his work.
During the academic session of 1872-3, he continued steadily at work at his investigations, and soon began to make rapid progress. At the beginning he had complained to me 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.