I can only describe by the theological term； 〃faiththe substance of things hoped for； the evidence of things not seen。〃 Both had been constrained to feel that the immutability of species could not be maintained。 Both； too； recognised the fact that it would be useless to proclaim this conviction； unless prepared with a satisfactory alternative to what Huxley called 〃the Miltonic hypothesis。〃 But Darwin's conviction was so far vital and operative that it sustained him while working unceasingly for twenty…two years in collecting evidence bearing on the question； till at last he was in the position of being able to justify that conviction to others。
And yet Lyell's attitudeand that of Hooker； which was very similar proved of inestimable service to science； as Darwin often acknowledged。 One of the greatest merits of the 〃Origin of Species〃 is that so many difficulties and objections are anticipated and fairly met； and this was to a great extent the result of the persistent and very candidif always friendlycriticism of Lyell and Hooker。
I think the divergence of mental attitude in Lyell and Darwin must be attributed to a difference in temperament； the evidence of which sometimes appears in a very striking manner in their correspondence。 Thus in 1838； while they were in the thick of the fight with the Catastrophists of the Geological Society； Lyell wrote characteristically： 〃I really find； when bringing up my Preliminary Essays in 〃Principles〃 to the science of the present day； so far as I know it； that the great outline； and even most of the details； stand so uninjured； and in many cases they are so much strengthened by new discoveries； especially by yours； that we may begin to hope that the great principles there insisted on will stand the test of new discoveries。〃 （Lyell's 〃Life； Letters and Journals〃； Vol。 II。 page 44。） To which the more youthful and impetuous Darwin replies： 〃BEGIN TO HOPE： why the POSSIBILITY of a doubt has never crossed my mind for many a day。 This may be very unphilosophical； but my geological salvation is staked on it。。。it makes me quite indignant that you should talk of HOPING。〃 （〃L。L。〃 I。 page 296。）
It was not only Darwin's 〃geological salvation〃 that was at stake； when he surrendered himself to his enthusiasm for an idea。 To his firm faith in the doctrine of continuity we owe the 〃Origin of Species〃； and while Darwin became the 〃Paul〃 of evolution； Lyell long remained the 〃doubting Thomas。〃
Many must have felt like H。C。 Watson when he wrote： 〃How could Sir C。 Lyell。。。for thirty years read； write； and think； on the subject of species AND THEIR SUCCESSION； and yet constantly look down the wrong road！〃 （〃L。L。〃 II。 page 227。） Huxley attributed this hesitation of Lyell to his 〃profound antipathy〃 to the doctrine of the 〃pithecoid origin of man。〃 （〃L。L。〃 II。 page 193。） Without denying that this had considerable influence （and those who knew Lyell and his great devotion to his wife and her memory； are aware that he and she felt much stronger convictions concerning such subjects as the immortality of the soul than Darwin was able to confess to） yet I think Darwin had divined the real characteristics of his friend's mind； when he wrote： 〃He would advance all possible objections。。。AND EVEN AFTER THESE WERE EXHAUSTED； WOULD REMAIN LONG DUBIOUS。〃
Very touching indeed was the friendship maintained to the end between these two leaders of thoughtfree as their intercourse was from any smallest trace of self…seeking or jealousy。 When in 1874 I spent some time with Lyell in his Forfarshire home； a communication from Darwin was always an event which made a 〃red…letter day；〃 as Lyell used to say； and he gave me many indications in his conversation of how strongly he relied upon the opinion of Darwinmore indeed than on the judgment of any other manthis confidence not being confined to questions of science； but extending to those of morals； politics； and religion。
I have heard those who knew Lyell only slightly； speak of his manners as cold and reserved。 His complete absorption in his scientific work； coupled with extreme short…sightedness； almost in the end amounting to blindness； may have permitted those having but a casual acquaintance with him to accept such a view。 But those privileged to know him intimately recognised the nobleness of his character and can realise the justice and force of Hooker's words when he heard of his death： 〃My loved； my best friend； for well nigh forty years of my life。 The most generous sharer of my own and my family's hopes； joys and sorrows； whose affection for me was truly that of a father and brother combined。〃
But the strongest of all testimonies to the grandeur of Lyell's character is the lifelong devotion to him of such a man as Darwin。 Before the two met； we find Darwin constantly writing of facts and observations that he thinks 〃will interest Mr Lyell〃； and when they came together the mutual esteem rapidly ripened into the warmest affection。 Both having the advantage of a moderate independence； permitting of an entire devotion of their lives to scientific research； they had much in common； and the elder manwho had already achieved both scientific and literary distinctionwas able to give good advice and friendly help to the younger one。 The warmth of their friendship comes out very strikingly in their correspondence。 When Darwin first conceived the idea of writing a book on the 〃species question；〃 soon after his return from the voyage； it was 〃by following the example of Lyell in Geology〃 that he hoped to succeed （〃L。L。〃 I。 page 83。）； when in 1844； Darwin had finished his first sketch of the work； and； fearing that his life might not be spared to complete his great undertaking； committed the care of it in a touching letter to his wife； it was his friend Lyell whom he named as her adviser and the possible editor of the book （〃L。L。〃 II。 pages 17…18。）； it was Lyell who； in 1856； induced Darwin to lay the foundations of a treatise （〃L。L。〃 I。 page 84。） for which the author himself selected the 〃Principles〃 as his model； and when the dilemma arose from the receipt of Wallace's essay； it was to Lyell jointly with Hooker that Darwin turned； not in vain； for advice and help。
During the later years of his life； I never heard Darwin allude to his lost friendand he did so very oftenwithout coupling his name with some term of affection。 For a brief period； it is true； Lyell's excessive caution when the 〃Origin〃 was published； seemed to try even the patience of Darwin； but when 〃the master〃 was at last able to declare himself fully convinced； he was the occasion of more rejoicing on the part of Darwin； than any other convert to his views。 The latter was never tired of talking of Lyell's 〃magnanimity〃 and asserted that； 〃To have maintained in the position of a master； one side of a question for thirty years； and then deliberately give it up； is a fact to which I much doubt whether the records of science offer a parallel。〃 （〃L。L。〃 II。 pages 229…30。）
Of Darwin himself； I can safely affirm that I never knew anyone who had met him； even for the briefest period； who was not charmed by his personality。 Who could forget the hearty hand…grip at meeting； the gentle and lingering pressure of the palm at parting； and above all that winning smile which transformed his countenanceso as to make portraits； and even photographs； seem ever afterwards unsatisfying！ Looking back； one is indeed tempted to forget the profoundness of the philosopher； in recollection of the loveableness of the man。
XIX。 DARWIN'S WORK ON THE MOVEMENTS OF PLANTS。
By FRANCIS DARWIN； Honorary Fellow of Christ's College； Cambridge。
My father's interest in plants was of two kinds； which may be roughly distinguished as EVOLUTIONARY and PHYSIOLOGICAL。 Thus in his purely evolutionary work； for instance in 〃The Origin of Species〃 and in his book on 〃Variation under Domestication〃； plants as well as animals served as material for his generalisations。 He was largely dependent on the work of others for the facts used in the evolutionary work； and despised himself for belonging to the 〃blessed gang〃 of compilers。 And he correspondingly rejoiced in the employment of his wonderful power of observation in the physiological problems which occupied so much of his later life。 But inasmuch as he felt evolution to be his life's work； he regarded himself as something of an idler in observing climbing plants； insectivorous plants； orchids； etc。 In this physiological work he was to a large extent urged on by his passionate desire to understand the machinery of all living things。 But though it is true that he worked at physiological problems in the naturalist's spirit of curiosity； yet there was always present to him the bearing of his facts on the problem of evolution。 His interests； physiological and evolutionary； were indeed so interwoven that they cannot be sharply separated。 Thus his original interest in the fertilisation of flowers was evolutionary。 〃I was led〃 （〃Life and Letters〃； I。 page 90。）； he says； 〃to attend to the cross…fertilisation of flowers by the aid of insects； from having come to the conclusion in my speculations on the origin of species； that crossing played an important part in keeping specific forms constant。〃 In the same way the value of his experimental work on heterostyled plants crystalised out in his mind into the conclusion that the product of illegitimate unions are equivalent to hybridsa conclusion of the greatest interest from an evolutionary point of view。 And again his work 〃Cross and Self Fertilisation〃 may be condensed to a point of view of great importance in reference to the meaning and origin of sexual reproduction。 （See Professor Goebel's article in the present volume。）
The whole of his physiological work may be looked at as an illustration of the potency of his theory as an 〃instrument for the extension of the realm of natural knowledge。〃 （Huxley in Darwin's 〃Life and Letters。〃 II。 page 204。）
His doctrine of natural selection gave； as is well known； an impulse to the investigation of the use of organsand thus created the great school of what is known in Germany as Biologya department of science for which no English word exists except the rather vague ter