GERMS, VACCINATION WITH DISEASE. 



347 



wig-Holstein. Princess Augusta was born on 

 January 25, 1860. It is regarded in Germa- 

 ny as particularly happy that the daughter of 

 the dispossessed Duke of Schleswig-Holstein 

 should thus become the future Empress of Ger- 

 many. 



GERMS, VACCINATION WITH DISEASE. Pas- 

 teur, in the course of his studies of anthrax 

 and chicken-cholera, has discovered means of 

 inoculating animals with milder forms of both 

 these diseases. This milder infection is found 

 to act as a safeguard against the virulent type 

 of the disease, as vaccination does against the 

 small-pox. The possible importance of the 

 principle established by Professor Pasteur in 

 dealing with the many deadly diseases which 

 are ascribed to the multiplication of minute 

 organisms can not be foreseen. The appli- 

 cation of this mode of prevention to splenic 

 fever, one of the most destructive and ineradi- 

 cable varieties of endemic infection known, has 

 already proved a signal success, and promises 

 to render harmless this scourge of the farm- 

 yard, which destroys five million dollars' worth 

 of domestic animals in France annually, and 

 vast numbers also in the other European coun- 

 tries and in Asia. After Pasteur had obtained 

 the vaccine for this disease, which is called an- 

 thrax fever, or splenic fever in English, ma- 

 lignant pustule being one of its forms, and 

 which in other countries is variously named 

 charbon in France, Milzbrand in Germany, and 

 the Siberian pest in Russia and after he had 

 demonstrated its efficacy by a public experi- 

 ment, he was not able at first to supply the 

 French farmers fast enough with the virus. 



The harmless germs are cultivated from the 

 ordinary malignant ones. The change is due 

 to the prolonged exposure of the bacteria, or 

 microbes, as Pasteur names these pathogenic 

 fungi collectively, to the influence of the oxy- 

 gen of the atmosphere. Microbes which are 

 cultivated in an infusion have their virulent 

 properties diminished in proportion to the 

 length of the exposure to the air without losing 

 their reproductive faculty. This was proved 

 to be due to the action of oxygen, by the fact 

 that an infusion which is kept hermetically 

 closed for any length of time remains capable 

 of producing the virulent form of infection. 

 When germs are cultivated, as in ordinary ex- 

 periments, by carrying the infection succes- 

 sively from one infusion to another, there does 

 not usually time enough elapse to allow oxy- 

 gen to be absorbed by the micro-organisms, in 

 quantities sufficient to modify the virulence of 

 the infection. But by allowing the infusions, 

 the first of which was infected with a minute 

 drop of the blood of a fowl which had died of 

 the cholera des poules, to rest exposed for 

 different periods before continuing them in 

 new infusions, it was found that the cultures, 

 when live fowls were inoculated, displayed 

 varying degrees of virulence. Thus it was 

 possible to obtain germs which showed any de- 

 gree of virulence the experimenter aimed to 



produce. From infusions which had been al- 

 lowed to ripen in this way he could produce 

 any desired proportion of mortality among the 

 chickens infected. By continuing the exposure 

 long enough, the microbes, while still capable 

 of propagating, lost all power of producing the 

 pathological symptoms. By examining the 

 tissue of the infected subject in which the 

 morbid symptoms had been produced in a 

 mitigated form, it was found to contain mi- 

 crobes of almost the same form, size, and ap- 

 pearance of those which cause the fatal dis- 

 ease. These germs of attenuated virulence 

 reveal their presence by a local disorder, which 

 runs a short course and then ceases. The 

 propagation of the disturbing organisms is ar- 

 rested by the power of nature to overcome the 

 morbific tendency, and the diseased tissue is 

 soon restored to its normal state. These lo- 

 calized and mitigated symptoms, if they have 

 not been too light, have the effect of hardening 

 the system against the disease, so that when 

 the animal which has thus been vaccinated is 

 inoculated with the fatal virus the malady does 

 not appear at all, or is only of a mild and tran- 

 sient type. Fowls which have been fortified 

 against the mortal infection by vaccination will 

 usually resist all the common conditions of 

 contagion for perhaps a year or longer. The 

 microbe of chicken-cholera, like many other 

 infectious microbes, does not propagate by 

 spores or germs, but by a process of scission. 

 One cell forms two or more, which arrange 

 themselves into loop-like forms, and then sepa- 

 rate to multiply further. True germs are sel- 

 dom developed in these cells. Other microbes 

 only multiply by the production of minute 

 germs within the cells. These germs or spores 

 are of infinitesimal size, but are capable of 

 preserving the vital principle of the parent 

 bacteria vigorous and unchanged, under the 

 most adverse conditions, and for a surprising 

 length of time. The microbes which propagate 

 by segmentation, on the other hand, perish of 

 starvation, after a few months, if their aliment 

 is limited. The Bacillus anthracis is one of 

 the most vigorous and persistent of the germ- 

 producing microbes. The conditions to the 

 problem of finding a counteracting vaccine, by 

 obtaining a modified type of the organism, 

 seemed much less propitious than in the case 

 of the chicken-cholera. Sheep were infected 

 by cropping grass over a spot where animals 

 which had died of anthrax had been buried 

 twelve years before. The spores had been 

 brought to the surface by earth-worms, and, 

 being taken in with the food of the sheep, de- 

 veloped into active microbes, which produced 

 the fatal symptoms in a few hours. The diffi- 

 culty was overcome by exposing the bacilli to 

 the influence of oxygen for prolonged periods 

 under conditions which would not allow them 

 to develop the corpuscle-germs. It was found 

 that in a certain kind of infusion of chicken- 

 flesh the propagation of the microbes, which 

 is impossible at the temperature of 45 Cent., 



