92 



NATURE 



\_Nov. 29, 1877 



mis and produces a mycelium, which develops in the very mass 

 of the fleshy tissue. Later there appear, in addition, fructiferous 

 filaments, which bear about twenty-five spores each. The cells 

 of the fruit, on passage of the parasite, are destroyed, and it is 

 thus that the crevices are formed. 



The diffusion which takes place between two gases separated 

 from each other by an absorbent film (f.^., a soap film) was 

 studied a short time ago by Prof. Exner, of the Vienra Aca- 

 demy. He has recently extended his inquiry to the case of 

 vapours from easily volatile liquids, using the same apparatus as 

 for permanent gases. The experiments were made with sulphide 

 of carbon, chloroform, sulphuric ether, benzine, alcohol, and oil 

 of turpentine, and they show that the diffusion from such vapours 

 follows the same laws as those of gases, i.e., that it depends both 

 on the coefficient of absorption of the film and on the density of 

 the gas being directly proportional to the former, and inversely 

 proportional to the square root of the latter. Thus it appears 

 that the greater or less distance of a gas from its liquefaction 

 point has at least no influence on this kind of diffusion. 



It is reported that Herr Josef Albert, the eminent Munich 

 photographer, has made the highly important invention of pho- 

 tographing the natural colours of objects by means of a combina- 

 tion of the ordinary photographic process with a photographic 

 printing press constructed by the same gentleman some time ago. 

 The images are stated to be so perfect that not the least improve- 

 ment with the brush is required, as the finest shades of colours 

 are faithfully reproduced. The secret of the invention is said to 

 be based on the separation of white light into yellow, blue, and 

 red rays, and in the artificial application of the same colours in 

 the printing press. The first negative is taken upon a plate 

 which is chemically prepared in such a manner that it only 

 receives the yellow tints or shades of the object ; this is then 

 passed through the printing press, the roller of which is impreg- 

 nated with a yellow colouring matter. On the print only the 

 yellow tints reappear more or less distinctly ; the object is then 

 again photographed, and this time a negative is prepared^which 

 only receives the blue shades and tints ; a second printing press 

 has its roller impregnated with some blue colour, and the plate 

 of course gives a print with only the blue tints reproduced. In 

 the same manner a third print is obtained which only shows the 

 red shades and tints. The final manipulation now consists in 

 printing the three images upon the same plate, when the three 

 colours intermingle and the natural colours and shades of th; 

 objects are obtained. We need hardly point out the enormous 

 importance of this invention. 



A PAMPHLET just published by the Director of the Paris 

 National Library contains some interesting statistical data re- 

 specting one of the finest libraries in the world. It has been 

 found that the library contains 86,774 volumes on catholic 

 theology, 44,692 volumes on the science of languages, 289,402 

 volumes on law, 68,483 volumes on medicine, 441,836 volumes 

 on French history, and 155,672 volumes of poetry. The works 

 on natural science are not yet catalogued. During 1876 the 

 library received no less than 45,300 French additions and 

 purchased 4,565 foreign books. 



The additions to the Zoological Society's Gardens during the 

 past week include two Black-eared Marmosets {Hapale penicillaia) 

 from South America, presented by Miss Quain ; a Black-backed 

 Jackal (Canis mesomeles) from South Africa, presented by Capt. 

 Fulton, s.s. Tay mouth Castle ; a Common Boa {Boa constrictor) 

 from South America, presented by Miss Alice Leith ; a Brown 

 Tree Kangaroo {Dendrolagus inustus) from New Guinea, a Slow 

 Loris {Nycticebus tardi^radiis) from Malacca, a River Jack Viper 

 ( Vipera rhinoceros) from West Africa, purchased ; a Green 

 '^lovkf-y [Ccrcofihecus callitric/ius) from West Afiica, deposited. 



1 



THE LIBERTY OF SCIENCE IN THE MODERN 

 STATED 



II. 



T is easy to say: "A cell consists of small particles, 

 and these we call plastidules ; plastidules, however, are 

 composed of carbon, hydrogen, oxygen, and nitrogen, and are 

 endowed with a special soul ; this soul is the product or the sum 

 of the forces which the chemical atoms possess." Indeei this 

 is possible ; I cannot judge of it exactly. This is om of those 

 points which are yet unapproachable for me ; I feel there like a 

 navigator who gets upon a shallow, the extent of which he cannot 

 guess. But yet I must say that before the properties of carbon, 

 hydrogen, oxygen, and nitrogen are defined to me in such a 

 manner that I can understand how, through their combination a 

 soul results, I cannot admit that we are justified in introducing the 

 plastidule soul into the educational programme or to ask gene- 

 rally of every educated min that he should recognise it as a 

 scientific truth to such a degree as to operate with it logically, 

 and to base tiis conception of the universe upon it. This we 

 may really not ask. On the contrary, I think that before we 

 designate such theses as the expression of science, before we say 

 this is modern science, we ought first of all to complete a whole 

 series of lengthy investigation'. We must therefore say to the 

 schoolmasters, do not teach this. This, gentlemen, is the re- 

 signation which in my opinion, those ought to exercise who 

 deem such a solution in itself to be the probable end of scientific 

 investigation. We can certainly not differ on that point for a 

 moment, that if this doctrine of the soul were really true it couli 

 only be confirmed by a long series of scientific investigations. 



There is a series of events in the field of the natural sciences, 

 by which we can show, for how long certain problems are in 

 suspense, before it is possible to find their true solution. If 

 this solution is found at last, and found in a direction of which 

 there was a presentiment perhaps centuries ago, it does not 

 follow that during those times which were occupied only by 

 speculation or presentiment the problem might have been taught 

 as a scientific fact. 



Prof. Klebs spoke of contapum animattim the other day, i.e. 

 the idea that in diseases the transmission takes place by msans 

 of living organisms, and that these organisms are the causes of 

 contagious diseases. The doctrine of conta^ium animtuvi loses 

 itself in the obscurity of the middle ages. We have had this 

 name handed down to us by our forefathers, and it is very 

 prominent in the sixteenth century. Certain works of that 

 period exist, which put down contagium animatum as a scientific 

 dogma with the same confidence, with the same kind of justi- 

 cation, as nowadays the plastidule soul is set up. Nevertheless 

 the living causes of diseases could not be found for a long time. 

 The sixteenth century could not find them, nor could the seven- 

 teenth and the eighteenth. In the nineteenth century we have 

 begun to find some contagia animata bit by bit. Zoology 

 and botany have both contributed to them : we have found 

 animals and plants which represent contagia, and a special 

 part of the knowledge of contagia has been absorbed into 

 zoology and botany, quite [in the sense of the theories of the 

 sixteenth century. But you will already have seen from the 

 address of Prof. Klebs that the end of proofs has not yet 

 ended. However much we may be disposed to admit 

 the general validity of the old doctrine, now that a series of 

 new living contagia have been found, now that we know 

 cattle disease and diphtheria to be diseases which are caused 

 by special organisms, still we may not yet say that now all 

 contagia or even all infectious diseases are caused by living 

 organisms. After it has appeared that a doctrine, which 

 was formulated already in the sixteenth century, and which has 

 since obstinately emerged again and again in the ideas of men, 

 has at last, since the second decade of the present century, 

 obtained more and more positive proofs for its correctness, we 

 might really think that no v it was our duty to infer, in the 

 sense of an inductive extension of our knowledge, that all con- 

 tagia and miasmata are living organisms. Indeed, gentlemen, 

 I will admit that this conception is an extremely probable one. 

 Even those investigators, who have not yet gone so far 

 as to regard the contagia and miasmata as living beings 

 have yet always said that they resemble living beings very closely, 

 that they have properties which we otherwise know in living 

 beings only, that they propagate their kind, that they increase 



' Address delivered at the Munich meeting of the Gennaa Association, 

 by Prof. Rudolf Virchow, of Berl'n. Continued from p. 74. 



