July 2, 1S96J 



NA TURE 



any fanciful resemblance between life and crystallisation, but to 

 disclose a fundamental difference ; not to bridge over the chasm 

 between animate and inanimate objects, but to widen the 



gulf- 

 Crystals are symmetrical individuals by virtue of their homo- 

 geneity. Organisms cannot be homogeneous in the same sense, 

 or they would possess the symmetry of crystals. One is led to 

 conclude that the organic individual is never homogeneous, but 

 consists of parts which are essentially different, just as the head 

 is different from the body, the leaf from the stem, or the shell 

 from the kernel. 



This I imagine to be the result to which biologists have been 

 led by quite independent reasoning ; every organic individual, 

 even the simplest possible individual, the cell, whether animal 

 or vegetable, consists of parts which are different ; a nucleus, 

 for example, and something distinct from llie nucleus. 



We may even proceed a step further, for more is implied in 

 this homogeneity than mere similarity of parts. It is also 

 necessary that the parts should not change places. A gas may 

 be homogeneous by virtue of the rapid and irregular movements 

 of its particles ; it may be the same at every point, because it is 

 throughout devoid. of any orderly arrangement. But this is not 

 the sort of homogeneity which leads to crystalline symmetry. 

 In the case of crystals there can be no taking the average of 

 crowds of irregularly moving particles, such as forms the basis 

 of the kinetic theory of gases ; there can be no talk of a drifting 

 of Liicretian atoms, although this was actually put forward as a 

 theory of crystal structure some years ago. 



Lord Kelvin's Boyle lecture on crystal tactics, which was 

 delivered in this very room three years ago, dealt with these 

 subjects, and it will be remembered that a crystal was in that 

 lecture regarded as constructed of a number of bodies placed side 

 by side in regular order, and all facing the same way. There 

 can be no doubt that the ultimate particles of a crystal are really 

 in motion, but their motions must be so circumscribed that none 

 encroaches upon its neighbour, and the crystal may therefore 

 be regarded as constructed of immovable units. In contrast 

 with this, I imagine that any organism, even any organic cell, 

 consists of parts which are not only different, but possess differ- 

 ential motions ; this fact is indicated, I presume, by the life of 

 any organism, and its growth by intussusception. 



Our final conclusion is, therefore, that the symmetry of a 

 mineral differs entirely from that of an organism, and is due to 

 its homogenity and the fixity of its parts. We have been led to 

 something resembling, in some degree, the Homoeomeria of 

 .\naxagoras. 



It is remarkable that the earliest writer concerning minerals, 

 whose works have survived, uses language which might almost 

 be applied to the discoveries of yesterday ; Theophrastus, in his 

 treatise on stones, says that the crystal must be regarded as 

 formed by the concretion of matter pure and equal in its 

 constituent parts, ix KaSapas rivhs irvpfaTauai Ka\ (ifia\risv\ris. 



Among modern writers, Herbert Spencer has most explicitly 

 .stated that there is some such distinction between living and non- 

 living things. He says: "Matter has two solid states, distin- 

 guished as colloid and crystalloid, of which the first is stable and 

 the second unstable. Organic matter has the peculiarity that its 

 molecules arc aggregated into the colloid and not into the 

 crystalloid arrangement." This almost amounts to .saying that 

 matter which lives cannot crystallise, and that crystallisable 

 matter cannot live. 



^'ou will now see that the inquiry with which we began has 

 led us far from our starting-point, and that, under the guise 

 of some reflections upon the beauty of minerals, I have really 

 been inflicting upon you a dissertation upon one of the most 

 abstruse problems of mathematical crystallography — that con- 

 cerning the ultimate structure of crystals. 



\'ou will also see that having proposed the question — What is 

 the origin and purpose of mineral beauty? — I have not been so 

 foolish as to attempt an answer, or to explain why minerals are 

 beautiful, but have merely asserted that their beauty, like all 

 their other properties, cannot have been acquired, and that in 

 this they differ from living things. 



My object in venturing on this difficult subject was two-fold. 

 In the first place, I was anxious to show that mineralogy, taken 

 even on its most abstract and most highly specialised side, over- 

 laps other sciences, even biology, with which it might be 

 expected to possess absolutely nothing in common. It brings us 

 face to face with problems relating to the nature of life. Those 

 who study the nature of living things cannot afford to ignore the 

 NO. 1392, VOL. 54] 



nature of crystals, any more than those who study the nature of 

 crystals can ignore that of living things. 



If to the chemist and physicist some knowledge of crystallo- 

 graphy is an absolute necessity, to the biologist it is at any rate 

 a matter of interest. 



Those who heard Lord Kelvin's Boyle lecture will have 

 realised both the importance and the difficulty of these specula- 

 tions relating to the ultimate structure of crystals ; speculations 

 which have attracted the keenest interest among many acute 

 thinkers. 



It is often forgotten that the earliest scientific work of the 

 great Frenchman, whose name is associated with some of the 

 most magnificent biological discoveries of the age, was in this 

 direction. Pasteur was, at the very outset of his career, attracted 

 l>y the relation between crystallisation and life. He imagined 

 that in a peculiar mode of .symmetry which he discovered in 

 certain crystals, he had found an es.sential difference between 

 living and non-living material, and that only such crystals 

 as present this particular symmetry are the products of life. 

 It has now been proved that such a symmetry is one which 

 results from crystalline homogeneity, and is therefore proper to 

 crystals ; but the interesting fact remains that Pasteur entered 

 upon his study of organisms by the way of crystallography, and 

 that the one was inextricably bound up with the other. 



Buckle saw in the history of mineralogy the .strongest confirma- 

 tion of his own views upon organic life. He regarded the early 

 discoveries of the great French mineralogist Haiiy, concerning 

 the form and structure of crystals, as one of the most important 

 contributions " to the magnificent idea that everything which 

 occurs is regulated by law, and that confusion and disorder are 

 impossible." Referring to the remarkable power possessed by 

 cry.stals, in common with animals, of repairing their own 

 injuries, he says : " However paradoxical such a noticn may be, 

 it is certain that symmetry is to crystals what health is to 

 animals. When therefore the minds of men became familiarised 

 with the great truth that in the mineral kingdom there is, 

 properly speaking, no irregularity, it became more easy for them 

 to grasp the still higher truth that the same principle holds good 

 of the animal kingdom." 



And this leads me to the second reason which I had for select- 

 ing my subject, namely, the excellent illustration which it affords 

 of the manner in which each branch of human thought not only 

 overlaps every other, but requires its support. 



If philosophic writers can illustrate their views by misleading 

 statements, it is because their illustrations are drawn from subjects 

 with which they have little personal acquaintance, and because 

 they have not consulted those who have made a special study of 

 such subjects. It seems to me that here in Oxford, above all 

 places, more might be done in the matter of mutual assistance, 

 and I am thinking not so much of the aid which might be given 

 by science to philosophy, as of the benefits which philosophy 

 might confer upon science. 



I have chosen for my text an instance in which philosophic 

 writers have confused two very different things — the individuality 

 of organisms, and the individuality of crystals, owing to their 

 imperfect acquaintance with the latter. It would have been 

 much easier and far more amusing to select instances in which 

 the scientific specialist has fallen into worse confusion owing to 

 his want of philosophic training. 



In Oxford, with our magnificent school of Literx Humaniores, 

 it seems disastrous that the science student .should not receive 

 .some of the crumbs that fall from her bounteous table— some 

 encouragement to that philosophic habit of thought in which he 

 acquires far too little training. I can only speak as a specialist, 

 but with the knowledge of what my own subject has suffered 

 through this need, and with the suspicion that this is equally the 

 ca.se with others. It is not for me to suggest how such an object 

 could best be attained ; but even if questions were asked in the 

 final school of natur.al science which would encourage attendance 

 at certain lectures on philo.sophy, I believe that science students 

 would gain much thereby. It would, no doubt, be equally 

 profitable for the philosophic student to gain some insight into 

 the matters and methods of modern science. 



I will conclude by quoting what Coethe has said about crystallo- 

 graphy. " It is," he says, " not productive ; it exists for itself 

 alone, and leads to no results. The mind derives from it within 

 limits a certain pleasure of satisfaction ; its details are so manifold 

 that it may be said to be in exhaustible." " For this reason," 

 he adds, "it has powerfully attracted the acutest intellects, and 

 has kept firm hold upon them." 



