300 



NA TURE 



{Jan. 27, 1887 



in falling into the sun, and are comparable with the 

 moderate little velocity (29'5 kilometres per second) of the 

 earth in her orbit round the sun. 



To fix the ideas, think of two cool solid globes, each of 

 the sami mean density as the earth, and of half the sun's 

 diameter, given at rest, or nearly at rest, at a distance 

 asunder equal to twice the earth's distance from the sun. 

 They will fall together and collide in half a year. The 

 collision will last for a few hours, in the course of 

 which they will be transformed into a violently agitated 

 incandescent fluid mass, with about eighteen million (ac- 

 cording to the Pouillet-Helmholtz reckoning, of twenty 

 million) years' heat ready made in it, and swelled out by 

 this heat to possibly one and a half times, or two, 

 or three, or four times, the sun's present diameter. If 

 instead of being at rest initially they had had a transverse 

 relative velocity of r42 kilometres per second, they would 

 just escape collision, and would revolve in equal ellipses 

 in a period of one year round the centre of inertia, just 

 grazing one another's surfaces every time they come round 

 to the nearest points of their orbits. 



If the initial transverse component of relative velocity 

 be less than, but not much less than, v \2 kilometres per 

 second, there will be a violent grazing collision, and two 

 bright suns, solid globes bathed in flaming fluid, will come 

 into existence in the course of a few hours, and will com- 

 mence revolving round their common centre of inertia in 

 long elliptic orbits in a period of a little less than a year. 

 The quasi-\^\diS\ interaction will diminish the eccentricities 

 of their orbits ; and if continued long enough will cause 

 the two to revolve in circular orbits round their centre of 

 inertia with a distance between their surfaces equal to 

 ■544 of the diameter of each. 



If the initial transverse component relative velocity of 

 the two bodies were just 6S metres per second, the moment 

 of momentum, the same before and after collision, would 

 be just equal to that of the solar system, of which seventeen- 

 eighteenths is Jupiter's and one-eighteenth the sun's: the 

 other bodies of the system being not worth considering 

 in the account. Fragments of superficially-melted solid, 

 or splashes of fluid, sent flying away from the main com- 

 pound mass could not possibly by tidal action or other 

 resistance get into the actual orbits of the planets, whose 

 evolution requires some finer if more complex fore-ordina- 

 tion than merely the existence of two masses undisturbed 

 by any other matter in space. 



I shall only say in conclusion : — Assuming the sun's 

 mass to be composed of portions which were far asunder 

 before it was hot, the immediate antecedent to its in- 

 candescence must have been either two bodies with 

 details differing only in proportion and densities from the 

 cases we have been now considering as examples ; or it 

 must have been some number more than two — some 

 finite number — at the most the number of atoms in the 

 sun's present mass, which is a finite number as easily 

 understood and imagined a5 number 3 or number 123. 

 The immediate antecedent to incandescence may have 

 been the whole constituents in the extreme condition of 

 subdivision — that is to say, in the condition of separate 

 atoms ; or it may have been any smaller number of 

 groups of atoms making up minute crystals or groups 

 of crystals — snowflakes of matter, as it were ; or it 

 may have been lumps of matter like this macadam- 

 ising stone ; or like this stone, which you might mis- 

 take for a macadamising stone, and which was actually 

 travelling through space till it fell on the earth at Fossil, 

 in the neighbouihood of Glasgow, on April 5, 1804 ; or 

 like this — which was found in the Desert of Atacama in 

 South America, and is believed to have fallen there from 

 the sky — a fragment made up of iron and stone, which 

 looks as if it has solidified from a mixture of gravel and 

 melted iron in a place where there was very little of 

 heaviness ; or this splendidly crystallised piece of iron, a 

 slab cut out of the celebrated aerolite of Lenarto, in 



Hungary ; ' or this wonderfully shaped specimen, a model 

 of the Middlesburgh meteorite, kindly given me by Prof 

 A. .S. Herschel, with corrugations showing how its melted 

 matter has been scoured off from the front part of its 

 surface in its final rush through the earth's atmosphere 

 when it was seen to fall on ."Vlarch 14, 1881, at 3.35 p.m. 



For the theory of the sun it is indifferent which of these 

 varieties of configurations of matter may have been the 

 immediate antecedent of his incandescence, but I can 

 never think of these material antecedents without remem- 

 bering a question put to me thirty years ago by the late 

 Bishop Ewing, Bishop of Argyll and the Isles: "Do 

 you imagine that piece of matter to have been as it is 

 from the beginning ; to have been created as it is, or to 

 have been as it is through all time till it fell on the earth ? " 

 I had told him that I believed the sun to be built up of 

 stones, but he would not be satisfied till he knew or could 

 imagine, what kind of stones. I could not but agree 

 with him in feeling it impossible to imagine that any one 

 of these meteorites before you has been as it is through 

 all time, or that the materials of the sun were like this 

 for all time before they came together and became hot. 

 Surely this stone has an eventful history, but I shall not 

 tax your patience longer to-night by trying to trace it con- 

 jecturally. I shall only say that we cannot but agree 

 with the common opinion which regards meteorites as 

 fragments broken from larger masses, but we cannot be 

 satisfied without trying to imagine what were the ante- 

 cedents of those masses. 



PROTOPLASM"- 



T T is a natural and beneficial result of the present 

 1 energetic pursuit of biological science that every 

 now and again some thinker comes forward to show us 

 where we stand, and to what our thoughts are impelling us. 

 Subordinate to the universal eminence and influence of 

 a LinnKus or a Darwin, the critics of a decade exert no 

 small effect on contemporary investigation by suggesting 

 new modes of viewing or expressing things ; and even 

 though the originality is not always happy, and the gene- 

 ralisations are sometimes unfortunate, it is nevertheless a 

 healthy sign that specialists of reputation, led to view 

 matters with a severely critical eye as their work pro- 

 gresses, occasionally turn round and warn us that it would 

 be as well to take stock of the facts, and see what are the 

 chances of solving some large problem. Moreover, it has 

 to be borne in mind that as various branches reach a 

 certain stage their results need overhauling by specialists 

 in other departments, and it becomes a question who is 

 to prepare the problems of biology, for instance, so that 

 the mathematician or the physicist may criticise them. 



As much on this account as for his own contributions 

 to the store of facts, we must welcome Dr. Berthold's 

 clever "Studies" as an earnest and important attempt to 

 contribute to a knowledge of the mechanics of life. Of 

 course it is always a difficulty to decide how far a special- 

 ist may be expected to take an accurate view of a large 

 problem to the direct solution of which his own re- 

 searches can contribute but little; but experience has 

 shown that more is to be looked for from the deep insight 

 obtained by close investigation than from the few brilliant 

 suggestions scattered through volumes of merely clever 

 thinking. In the present case, the moderate tone of the 

 book, and the easy earnestness of the writer, should at 

 least insure careful reading of the 324 pages of text in 

 which Dr. Berthold expresses his bold ideas ; and whether 

 the conclusions stand or fall, the reader will be amply 

 repaid by the observations collected and the criticisms on 

 several questions now agitating the minds of botanists. 



' The three aerolites now exhibited belong to the Hunterian Museum of 

 the University of Glasgjw, and have been kindly lent me for this evening 

 by the Curatur, Dr. Young. 



- "Studien liber Protoplasmamechanik." By Dr. G. Berthold. Professor 

 of Botany in the University of Gottingen. (Leipzig: Arthur Felix, 1886.) 



