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SCIENCE. 



[Vol. XX. No. 516 



SCIENCE; 



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ON NATURAL AND ARTIFICIAL IMMUNITY. 



BY O. LOEW, MEMBER OF THE UNIVERSITY OF MUNICH, FORMERLY 

 MEMBER OF THE WHEELER EXPEDITIONS, WEST OP THE 100th 

 MERIDIAN, OF THE TJ. S. CORPS OP ENGINEERS. 



Since the beginning of the extensive bacteriological investiga- 

 tions of Pasteur, about twenty years ago, the new-born science 

 of bacteriology has developed to gigantic proportions, and, 

 although this science is still in its youth and capable of an im- 

 mense extension, it has become of an extraordinary importance 

 and of universal interest. No other science can boast of such 

 rapid development. Many investigators, botanists, hygienists, 

 physicians, and chemi.sts, have contributed their share to raise 

 the science to an imposing figure. We name here above all : C. 

 Nageli, R. Koch, Ru'iolf Emmerich, Hans Buchner, M. Nencki, 

 the Italians Tittoni and Cattani, the Americans Billings and 

 Dixon, the Japanese Kitasato and Tsuboi, the Englishman Han- 

 kin, and the Germans Hilppe, Scholl, and Baumgarten. 



It was Koch who invented excellent methods of isolating dif- 

 ferent bacteria species and made us acquainted with the bacillus 

 of tuberculosis and the comma-bacillus; Kitasato isolated for the 

 first time the bacillus of influenza and of tetanus (lockjaw); 

 Nencki, Krieger, Hiippe, and Scholl isolated poisonous albumi- 

 nous products of different bacteria species. But it was essen- 

 tially Professor Rudolf Emmerich of Munich,' whose everlasting 

 merit it is to have taken the first successful steps for solving the 

 mystery of natural and artificial immunity. 



We know now that nine-tenths of all diseases of man and ani- 

 mals are due to certain bacteria species that either by the lungs 

 or by the stomach enter the body, multiply in the blood, and 

 yield poisonous secretions that finally attack the nervous system 

 and bill the body if no powerful reaction sets in that kills the bac- 

 teria, while their poisonous secretions ate expelled by the body 

 by oxidation or by the excreta. 



Now, this reaction against bacterial evil-doings is the most in- 

 teresting and marvellous process in the science of bacteriology 

 and medicine, a process that was surrounded by a deep mystery, 

 and the more interesting as it became evident that an animal 

 having passed through a certain infectious disease, had acquired 

 a certain resistance for a cprtain period against the same cause 

 of disease. Experiments of Pasteur had shown this to be the case 

 in various diseases. This resistance gained by passing through 

 an infectious disease is known by the name of artificial im- 

 munity. 



There exists, however, also a natural immunity, that is, the re- 

 sistance of certain animal species against certain kinds of bac- 

 teria, without ever having passed through an infectious disease. 

 For instance, rats and dogs are incapable of getting tuberculosis 



^ Professor Emmerich Is tlie most successful student of the far-famed hy- 

 gleniat, Professor Dr, Max v.. Pettenkofer of MuDicb. 



or swine plague (roth lanf), rats are incapable of anthrax, most 

 animals are incapable of typhoid fever and Asiatic cholera. 



It was Professor Emmerich who discovered first, in 1886, that 

 the blood of an animal that had recovered from an infectious dis- 

 ease can cure another animal from the same disease or even pre- 

 vent the development of the same disease if subcutaneous injec- 

 tions are made. He had proved, for the first time, that the bac- 

 teria in question are killed rapidly in the blood of an animal that 

 had acquired immunity. He supposed, at that time, that there 

 are formed certain albuminous combinations that act as poisons 

 upon the barteria. Sometime afterwards. H. Buchner proved 

 indeed that the fresh blood of various animals contains albumi- 

 nous bodies detrimental to bacteria and that the natural immunity 

 is thus easily explained, while for the artificial immunity this 

 was proved later by Emmerich. This was to many a remarkable 

 surprise, for all albuminous substances had been heretofore con- 

 sidered as the best nutrition for every living cell. 



But this surprise was not altogether justified, for two Ameri- 

 cans, S. Weir Mitchell and Edward Reichert, had demonstrated 

 that the poison of the rattlesnake consists of two albuminous 

 bodies, and a little later such poisonous combinations have been 

 isolated from the seeds of Abras preratoriiis and of liicinus com- 

 munis. Now, if there existed albuminous bodies noxious for the 

 higher animals and not for bacteria, there could not more be won- 

 dered at, if albuminous bodies existed noxious to bacteria and 

 not for animals. There exists, however, a third class of albumi- 

 nous substances (proteids) noxious to both animals and bacteria. 



Here must be mentioned, also, the theory of Metschnikoff in 

 regard to the disappearance of bacteria in the blood of an infected 

 animal. He had observed that the while blood-corpuscles or 

 lymphatic cells devour living bacilli, for instance, the bacteria 

 of anthrax, and he believed therefore, this to be the principal 

 way to get rid of the entered bacteria. This theory of the 

 phazorytose, however, did not give sufficient explanation in 

 several regards. 



The investigations of Professor Rudolf Emmerich have shown 

 us that the albuminous bodies of the serum of dogs' blood, when 

 precipitated by alcohol and redissolved in water containing 0.4 

 p. mille caustic soda had raicrobicide properties even then, if by 

 the treatment with alcohol this property had been lost in conse- 

 quence of a slight chemical change. Thrs proved that a certait* 

 atomic constitution can be restituted by the very diluted solution 

 of caustic soda. Not so easily changeable by alcohol is, how- 

 ever, the albuminous body causing the artificial immunity, as 

 Emmerich has found, and while it is easy to cure with blood of 

 artificially immunized animals, no one was able until now to ob- 

 serve a cure by application of blood of naturally immune animals. 

 One cannot immunize, for instance, with dog's blood against 

 tuberculosis of man or with the blood of rabbits against typhoid 

 fever. 



Professor Emmerich and Professor Tsuboi have investigated 

 the blood of rabbits that were artificially immunized against 

 swine-plague (roth lauf). The serum of this blood was (after 

 separation of the globulin) concentrated at 42° C. in vacuo, 

 whereby an albuminous body of prominent curing properties was 

 precipitated. The filtered liquid, however, gave upon precipita- 

 tion with alcohol also a substance of the same curing qualities. 

 This substance was washed with alcohol and ether and dried at a 

 low temperature. This dry powder possessed all the curing prop- 

 erties of the blood itself against swine- plague. Thus we have 

 for the first time the curing substance (Heilsubstanz) in a dry state, 

 although mixed yet with inactive albuminous substance. This 

 is a fact of immense importance, the most important discovery in 

 bacteriology relating to medicine. Emmerich and Tsuboi gave also- 

 a plausible theory in regard to the formation and the mode of ac- 

 tion of this remarkable substance, as may be studied in their 

 publication, " Die Natur der Schutz und Heilsubstanz des Blu- 

 tes," Wiesbaden, 1892. We hope to communicate later more of 

 the investigations of Emmerich and Tsuboi. 



A few additional remarks may be permitted to the writer. 

 The great admirable transatlantic republic, with its unrivalled 

 wonderful development, with its immense natural resources, and 

 an unbegrd of liberality and magnanimity and generosity of 



