June 21, 1883] 



NATURE 



187 



in addition to those mentioned in rny paper read before the 

 Royal Society, will, I hope, justify me in having advanced a 

 theory of magnetism which I believe in every portion allows at 

 least experimental evidences of its probable truth. 



THE REDE LECTURE 



THE following abstract report of Prof. Huxley's Rede 

 Lecture given on Tuesday week in the Cambridge 

 Senate House, to a crowded audience, has been revised, 

 to the extent of removing any errors of importance, 

 by the author. We understand that a full report of the 

 lecture will shortly be published in a separate form. 



Professor Huxley said he had undertaken to treat in the 

 course of such time as custom and the patience of his audience 

 might permit, on a very great subject, no less a subject than the 

 origin of all those forms of animal life which at present existed. 

 It had behoved him to restrict what he might lay before them to 

 those considerations which were absolutely essential for his 

 purpose, and he should endeavour to lay before them facts of 

 such an order as appeared to him to be of most importance in 

 reference to his argument. Although he might fail to put those 

 lacts before them as clearly as they presented themselves to his 

 own mind, the reasonings which might be based upon them were 

 of so simple an order th it he should consider his task performed 

 if he gave the 11 a tolerably clear concepti in of what those facts 

 were, for he did n it think it was the business of a man of science 

 to use the arts of rhetoric or endeavour to procure persuasion. 

 His sole business uj^ to place the facts before those whom he 

 wished to teach, and to leave it to their reason to form such 

 judgment upon those facts as they might think fit. In the 

 present case he should point out to them what judgments such 

 facts had forced upon his mind, but he must leave it entirely to 

 their responsibility to say what judgment they might con train 

 them to give in their case. They lni'ht a-sume this position at 

 starting, that, whatever in such a milter was true for one animal, 

 was true for the infinite series of the whole animal world ; and 

 as he was extremely anx ous to avoid everything speculative, 

 everything th it could not lie directly led back to the matters of 

 fact upon which it was based, he proposed to select one animal 

 particularly, and to put before them facts and arguments by the 

 help of which they might form some probable c inclu-ion as to 

 the origin of that object. He took it for granted that, if the 

 evidence inclined towards a particular conclusion in the case of 

 that animal, they might assume that it would incline in the same 

 direction with regard to all. He had no doubt that a great many 

 of his audience were familiar at any rate with the shell of the 

 animal about which he was going to speak, namely, that of the 

 pearly nautilus, from which, or parts of which, very beau- 

 tiful ornaments were fabricated. At the present time the 

 nautilus inhabited the warmer parts of the Indian and Pacific 

 Oceans, living at considerable depths and preying upon the hard 

 shelled crustaceans and mollusks that crept along the bottom, 

 and which it found in its way. For that end it wa> provided 

 with a very curi us beak, shaped like that of a parrot, but with 

 each portion covered with a hard calcareous deposit, and « hich 

 enabled it to be an efficient instrument for crushing its prey. If 

 he were to touch upon the morphological problem « hich here 

 presented itself, he cuuld occupy far more time than they had at 

 their disposal with the consideration of a multitude of interesting 

 peculiarities which the nautilus presented, for it was one of those 

 forms which at present stood almost isolated and aloae in the 

 animal world, separated by a wide gulf from its nearest allies, 

 tho-e animals which they knew as squids and cuttle-fishes. It 

 held the middle place between sea-snails and the group of the 

 cuttle-fishes. It would be, however, entirely out of place at 

 present, and a purposeless waste of time if he w ere to touch upon 

 any peculiarities except those which would be needed during his 

 further argument. The only points to which he would direct 

 their attention for that purpose were the facts which related to 

 the structure of the shell. There was a diagram beside him 

 showing a part of the nautilus shell in section, but he thought it 

 possible that he could make the matter clearer by roughly sketch- 

 ing on the board the main points as he went on. — Prof. Huxley 

 here des.-ribed, with the aid of diagrams, preserved speci- 

 mens, and models, the complicated structure of the shells 

 of the pearly nautilus, or Nautilus pompilius. The animal 

 itself was contained in the spacious chamber in the outer part of 

 the shell, which was divided from the rest of the shell by a par- 



tition. The rest of the shell resembled a long cone closely coiled 

 up, and divided by partitions at regular intervals into other 

 chambers, which succeeded one another, and in the full-grown 

 animal were full of air. From the hinder part of the animal's 

 body a long tube, the siphuncle, was carried backwards through 

 the whole of the shell, and as it completely filled up the openings 

 in the partitions through which it passed there was no com- 

 munication between one chamber and another. The first point 

 to be considered was as to what was the origin of the particular 

 nautilus in the bottle before him. Happily there was no dispute 

 upon that point. 1 he female nautilus contained eggs exactly as 

 the hen did. These eggs were small masses of protoplasmic 

 matter, each containing a nucleus in its centre, which was all 

 that was essential. They knew that that pearly nautilus with all 

 nplicated organism, and fitted with the complicated shell 

 he had described, did, in some way or other, proceed from that 

 relatively structureless body which they called the egg or the ovum. 

 As fate would have it, up to the present they had Known nothing 

 from direct observation of the process by which that pirticular 

 animal was produced from this microscopic particle. But they 

 had so large a knowledge of the process in other animals "I every 

 description that there was no doubt whatever as to the nature of 

 the process, which he would try to describe to them as briefly 

 as possible, by reference to the process which took place in the 

 case of the domestic hen. Neither by the highest (lowers of the 

 microscope, nor by other means of investigation which they had 

 at present, could they trace anything in the slightest degree 

 resembling either the chick, which under certain circumstances 

 led from that egg, or the tissues of the chick. There 

 was, however, one spot on the yolk of the egg, a little careful 

 observation of which would show a clear space, which might be 

 a fifth of an inch in diameter. It was very well known by the 

 name of the cicatricula, or little scar. He would sup. pose that 

 twenty-one eggs w ere placed together under the hen. If they 

 took one egg day by day and examined it they would know what 

 took place as if they had watched continuously, for what hap- 

 pened in any one egg happened also in the others. That was 

 .1 process — the wonder of which he must confess never staled in 

 his mind — by which the chick was gradually fshioned out of 

 that transparent rudiment. They saw it make its appearance in 

 the first place on the surface of the yolk, and to the naked eye 

 it looked like a white streak. That white streak gradually 

 assumed the appearance of a sort of elongated body, and that 

 body shaped itself so that it could be seen that it was going to 

 be an animal of some kind, it having a large head, and the 

 rudiments of eyes and vertebra;. On the fifth day they could 

 clear!) see « hat they were going to have. Gradually, step by 

 step, and moment by moment, new differences made their appear- 

 ance from the original foundation, and until many days before 

 batching there was an unmistakable bird, and at the twenty- 

 first day there emerged from the shell an animal endow ed with 

 all a bird's capacities and structures. That process was the process 

 of development. If they inquired into the nature of the cicatricula, 

 thev would find that that was merely a double layer of minute 

 nucleated cells. They would find that that resulted from the 

 splitting up of a protoplasmic mass that had been there before. 

 They could trace the process back into the body of the hen 

 until they came dawn to a simple nucleated cell, so that it was 

 a matter capable of demonstration that in that nucleated cell 

 which formal a part of the egg organ of the hen — in that 

 particle of, far morphological purposes, structureless jelly, 

 were the same characteristics which were possessed by the 

 very lowest forms of animal life which were known. They 

 knew that in that particle resided a potentiality, capable of 

 developing itself through the stages he had roughly indicated, 

 until it became not only a machine of the highest order 

 from a physiological point of view", but a very remarkable 

 work of art. That particle of protoplasmic matter did that 

 in virtue of the po vers inherent in its material nature. That 

 was the point he wished to put lief ire them as clearly and defi- 

 nitely as he could, because it would be fundamental in all further 

 discussion. For it was to the process he had briefly described that 

 the great di-coverers of the last two centuries applied the name of 

 "evolution." Singularly enough the persons who fir t used that 

 name did not use it in that sense in which it was universally used 

 now, becau e they were under a mistake as to the exact nature 

 of the process. Hut the whole conception of evolution was now 

 based upon ascertained facts, sh awing the process of develop- 

 ment of the most complicated animal out of a relatively struc- 

 tureless particle, which had no higher organisation than that of the 



