October, 1875, a detailed account of his Observations and Views on the Development of the Urogenital Organs.

Some time in August of the same year he started in company with Mr Arthur Evans and Mr J. F. Bullar for a second trip to Finland, the travellers on this occasion making their way into regions very seldom visited, and having to subsist largely on the preserved provisions which they carried with them, and on the produce of their rods and guns. From a rough diary which Balfour kept during this trip it would appear that while enjoying heartily the fun of the rough travelling, he occupied himself continually with observations on the geology and physical phenomena of the country, as well as on the manners, antiquities, and even language of the people. It was one of his characteristic traits, a mark of the truly scientific bent of his mind, of his having, as Dohrn soon after Balfour's first arrival at Naples said, 'a real scientific head,' that every thing around him wherever he was, incited him to careful exact observation, and stimulated him to thought.

In the early part of the Long Vacation of the same year he had made his first essay in lecturing, having given a short course on Embryology in a room at the New Museums, which I then occupied as a laboratory. Though he afterwards learnt to lecture with great clearness he was not by nature a fluent speaker, and on this occasion he was exceedingly nervous. But those who listened to him soon forgot these small defects as they began to perceive the knowledge and power which lay in their new teacher.

Encouraged by the result of this experiment, he threw himself, in spite of the heavy work which the Elasmobranch investigation was entailing, with great zeal into an arrangement which Prof. Newton, Mr J. W. Clark and myself had in course of the summer brought about, that he and Mr A. Milnes Marshall, since Professor at Owens College, Manchester, should between them give a course on Animal Morphology, with practical instruction, Prof. Newton giving up a room in the New Museums for the purpose.

In the following October (1875) upon Balfour's return from Finland, these lectures were accordingly begun and carried on by the two lecturers during the Michaelmas and Lent Terms. The number of students attending this first course, conducted on a novel plan, was, as might be expected, small, but the Lent Term did not come to an end before an enthusiasm for morphological studies had been kindled in the members of the class.

The ensuing Easter term (1876) was spent by Balfour at Naples, in order that he might carry on towards completion his Elasmobranch work. He had by this time determined to write as complete a monograph as he could of the development of these fishes, proposing to publish it in instalments in the Journal of Anatomy and Physiology, and subsequently to gather together the several papers into one volume. The first of these papers, dealing with the ovum, appeared in Jan. 1876; most of the numbers of the Journal during that and the succeeding year contained further portions; but the complete monograph did not leave the publisher's hands until 1878.

He returned to England with his pupil and friend Mr J. F. Bullar some time in the summer; on their way home they passed through Switzerland, and it was during the few days which he then spent in sight of the snow-clad hills that the beginnings of a desire for that Alpine climbing, which was destined to be so disastrous, seem to have been kindled in him.

In October, 1876, he resumed the lectures on Morphology, taking the whole course himself, his colleague, Mr Marshall, having meanwhile left Cambridge. Indeed, from this time onward, he may be said to have made these lectures, in a certain sense, the chief business of his life. He lectured all three terms, devoting the Michaelmas and Lent terms to a systematic course of Animal Morphology, and the Easter term to a more elementary course of Embryology. These lectures were given under the auspices of Prof. Newton; but Balfour's position was before long confirmed by his being made a Lecturer of Trinity College, the lectures which he gave at the New Museums, and which were open to all students of the University, being accepted in a liberal spirit by the College as equivalent to College Lectures. He very soon found it desirable to divide the morphological course into an elementary and an advanced course, and to increase the number of his lectures from three to four a week. Each lecture was followed by practical work, the students dissecting and examining microscopically, an animal or some animals chosen as types to illustrate the subject-matter of the lecture; and although Balfour had the assistance at first of one[2], and ultimately of several demonstrators, he himself put his hand to the plough, and after the lecture always spent some time in the laboratory among his pupils. Had Balfour been only an ordinary man, the zeal and energy which he threw into his lectures, and into the supervision of the practical work, added to the almost brotherly interest which he took in the individual development of every one of the pupils who shewed any love whatever for the subject, would have made him a most successful teacher. But his talents and powers were such as could not be hid even from beginners. His extensive and exact knowledge, the clearness with which in spite of, or shall I not rather say, by help of a certain want of fluency, he explained difficult and abstruse matters, the trenchant way in which he lay bare specious fallacies, and the presence in almost his every word of that power which belongs only to the man who has thought out for himself everything which he says, these things aroused and indeed could hardly fail to arouse in his hearers feelings which, except in the case of the very dullest, grew to be those of enthusiasm. His class, at first slowly, but afterwards more rapidly, increased in numbers, and, what is of more importance, grew in quality. The room allotted to him soon became far too small and steps were taken to provide for him, for myself, whose wants were also urgent, and for the biological studies generally, adequate accommodation; but it was not until Oct. 1877 that we were able to take possession of the new quarters.

Even this new accommodation soon became insufficient, and in the spring of 1882 a new morphological laboratory was commenced in accordance with plans suggested by himself. He was to have occupied them in the October term, 1883, but did not live to see them finished.

As might have been expected from his own career, he regarded the mere teaching of what is known as a very small part of his duties as Lecturer; and as soon as any of his pupils became sufficiently advanced, he urged or rather led them to undertake original investigations; and he had the satisfaction before his death of seeing the researches of his pupils (such as those by Messrs. Bullar, Sedgwick, Mitzikuri, Haddon, Scott, Osborne, Caldwell, Heape, Weldon, Parker, Deighton and others) carried to a successful end. In each of these inquiries he himself took part, sometimes a large part, generally suggesting the problem to be solved, indicating the methods, and keeping a close watch over the whole progress of the study. Hence in many cases the published account bears his name as well as that of the pupil.

In the year 1878 his Monograph on Elasmobranch Fishes was published as a complete volume, and in the same year he received the honour of being elected a Fellow of the Royal Society, a distinction which now-a-days does not often