nan 



deaf ear In this respect? 



ADDENDUM. 



THE foregoing sentences on this pago gave 

 rise to a controversial attack by Mr. J. C. F. 

 Zoellner, in his book " On the Nature of the 

 Comets," on Sir W. Thomson, on which I took 

 occasion to express myself briefly in the pre- 

 face to the second part of the German transla- 

 tion of the " Handbook of Theoretical Phy- 

 sics," by Thomson and Tait. I give here the 

 passage in question : 



M I will mention here a further objection. 

 i!t refers o the question as to the possibility 

 that organic germs may occur in meteoric 

 stones, and be conveyed to the celestial 

 bodies which have been cooled. In his 

 opening Address at the Meeting of the British 

 Association in Edinburgh, in August, 1871, 

 Sir W. Thomson had described this aa ' not 

 unscientific.' Here also, if there is an error, 

 I must confess that I also am a culprit. I 

 had mentioned the same view as a possible 

 mode of explaining the transmission cf organ- 

 isms through space, even a little before Sir 

 W. Thomson, in a lecture delivered in the 

 spring of the same year at Heidelberg and 

 Cologne, but not published. I cannot object 

 if any one considers this hypothesis to be in 

 a high, or even in the highest, degree im- 

 probable. But to me it seems a perfectly 

 correct scientific procedure, that when all 

 our attempts fail in producing organisms 

 from inanimate matter, we may inquire 

 whether life has ever originated at all or not, 

 and whether its germs have not been trans- 

 ported from one world to another, and have 

 developed themselves wherever they found a 

 favorable soil. 



" Mr. Zoellner' s so-called physical objec- 

 tions are but of very small weight. He re- 

 calls the history of meteoric stone, and 

 adds (p. xxvi. ) : 'If, therefore, that meteoric 

 stones covered with organisms had escaped 

 with a whole skin in the smash-up of its 

 mother-body, and had not shared the general 

 rise of temperature, it must necessarily have 

 first passed through the atmosphere of the 

 earth before it could deliver itself of its 

 organisms for the purpose of peopling the 

 earth.' 



Now, in the first place, we know from 

 repeated observations that the larger mete- 

 oric stones only become heated in their out- 

 side layer during their fall through the at- 

 mosphere, while the interior is cold, or even 

 very cold. Hence all germs which there 

 might be in the crevices would be safe from 

 combustion in the earth's atmosphere. But 

 even those germs which were collected on 

 the surface when they reached the -highest 

 and most attenuated layer of the atmosphere 

 would long before have been blown away by 

 the powerful draught of air, before the stone 

 reached the denser parts of the gaseous mass, 

 where the compression would be sufficient 

 to produce an appreciable heat. And, on 

 the other hand, as far as the impact of two 

 bodies is concerned, as Thomson assumes, 



POPULAR SCIENTIFIC LECTURES. 



the lirst consequences would be powerful 

 mechanical motions, and only in the degree 

 in which this would bo destroyed by friction 

 would heat be produced. Wo do not knovr 

 whether that would last for hours, for da\ s. 

 or for weeks. The fragments, which at tin.- 

 first moment were scattered with planetary 

 velocity, might escape without any disi-n- 

 gagement of heat. I consider it even not 

 improbable that a stone, or shower of stones, 

 flying through the higher regions of the at- 

 mosphere cf a celestial body, carries with it 

 a mass of air which contains unburm d 

 germs. 



" As I have already remarked, I am not in- 

 clined to suggest that all these possibilitisH 

 are probabilities. They are questions th 

 existence and signification of which wo must 

 remember, in order that if the case arise thc-v 

 may be solved by actual observations or by 

 conclusions therefrom." 



ON THOUGHT IN MEDICINE. 



A ADDRESS DELIVERED AUGUST 2, 1877, ON 

 THS ANNIVERSARY OP THE FOUNDATION OF 

 THE INSTITUTE FOB THE rDUCATTON OP ABMY 

 8UEGEON8. 



IT is now thirty-five years since, on the 24 

 of August, I stood on the rostrum in the Hall 

 of this Institute, before another such audi- 

 ence as this, and read a paper on the opera- 

 tion of Venal Tumors. I was then a pupil 

 of this Institution, and was just at the end 

 of my studies. I had never seen a tumor cut, 

 and the subject-matter of my lecture was 

 merely compiled from books; but book knowl- 

 edge played at that time a far wider and a 

 far more influential part in medicine than we 

 are at present disposed to assign to it. It 

 was a period of fermentation, of the fight be- 

 tween learned tradition and the new spirit of 

 natural science, which would have no more 

 of tradition, but wished to depend upon in- 

 dividual experience. The authorities at that 

 time judged more favorably of my essay tlran 

 I did myself, and I still possess the books 

 which were awarded to rue as the prize. 



The recollections which crowd in upon me 

 on this occasion have brought vividly before 

 my mind a picture of the then condition of 

 our science, of our endeavors and of our 

 hopes, and have led mo to compare the paat 

 state of things with that into which it has 

 developed. Much indeed has been accom- 

 plished. 



Although all that we hoped for has not 

 been fulfilled, and many things have turned 

 out differently from what we wished, yet wo 

 have gained much for which we could not 

 hare dared to hope. Just as the history of 

 the world has made one of its few giant steps 

 before our eyes, so also has our science ; 

 hence an old student, like myself, scarcely 

 recognizes the somewhat matronly aspect of 

 Dame Medicine, when he accidentally coinee 



