14t 



♦ KNOWLEDGE ♦ 



[Feb. 20, 1885. 



architect's plan ; the wrong ones do both their construction 

 and their destruction in a miscliievou.? way. 



If an infusion of hay is kept for some time, vaiious 

 species appear in succession. This is partly because 

 some have a quicker rate of growth than others, but also 

 because some microferments, at one time, make the solu- 

 tion fit for certain creatures to develop in, and other 

 ferments eflfect furtlur changes that are adapted to other 

 kinds. 



The above remarks are intended to introduce a brief 

 account of the progress lately made in the discovery of 

 disease germs, and in their modification so as to render 

 thsm promoters of safety, instead of agents of destruction. 



The first evidence of attenuation of virus by cultivation 

 under fresh conditions was obtained by Jenner, and more 

 recent experimenters have shown cow-pox can be given to 

 cattle by inoculation with smallpox germs. M. Boucharda*, 

 alluding to the controversies on this subject, says, " that 

 which res's indubitable is that by vaccinating after the 

 niethod of Tiiiel6 and CVeley, the inoculation of the parasite 

 of small-pox has been rendered inoffensive, while preserving 

 its protective property. In passing from the man to the 

 cow, and back from the cow to the man it has lost its noxious 

 properties and retained its useful ones." 



The microferment producing measles [rouget) in pigs has 

 afforded cui'ious results in the experiments of Pasteur and 

 Thuillet. Its transference from the pig to some animals 

 increased its virulence, while in other animals it has 

 diminished. It killed pigeons in a few days, and was 

 transmitted from pigeon to pigeon in a virulent i-tate. 

 From pigeon back to pig it was much more virulent than 

 from one pig to another. From pig to rabbit it was 

 generally fatal to the latter, and continued so when passed 

 from rabbit to rabbit. But, says M. Boui hardat, " culti- 

 vations of gerrns in the blood of these rabbits in a sterilised 

 oiedium became more and more easy and abundant ; the 

 microbe changed its aspect a little, becoming stouter than 

 in the pig, and sometimes .shaped like a figure 8, without 

 filiform elongation." After successive cultivation in 

 rabbits, its action upon pigs became less virulent. It no 

 longer killed them, but acted as a preservative against their 

 own form of the disorder. 



In Pasteur's experiments with the virus of rabies, the 

 saliva of mad animals was found to contain divers 

 organisms ; but as the disease affected the brain, the parasite 

 was sou"ht for there, and in the spinal marrow and in the 

 nerves, especially the puemogastric* M. Boucliardat 

 tells us in his resiimr tha*". " these parasites, of one species 

 or another, may develop in man or animal up to a certain 

 jioint without occasioning disturbance ; but the day comes 

 when from their numVjers or their attacking certain parts 

 of the nervous system, the terrible symptoms of rabies, or 

 cerebral syphilis appeir." The precise symptoms of the 

 madness de]iend upon the parts of the brain that are 

 attacked. The virus of this terrible disorder augments by 

 its cultivation in certain animals, as when tranhferred 

 from rabbit to rabbit, or guinea-pig to guinea-pig, or from 

 these animals to the dog. From dog to menkey, and from 

 monkey to monkey, the poison is attenuated, and can be so 

 reduced as not to be injurious, but, on the contrary, a pre- 

 servative to a dog. 



The microbe-producing septicemia (blood-poisoning) 

 admits of similar modification. M. Pasteur has saved 

 thousands of cattle, sheep, and poultry from the diseases 

 produced by microbes, and he hopes that hydrophobia may 

 ill time be extirpated. Besides the security against 



* The pnemogastric is the longest of all the cranial nerves, as it 

 supplies not only the organs of the voice and of respiration, but also 

 the heirt ami stomach. — Mivart. "Elementary Anatomy." 



terrible diseases affecting men and animals by the method 

 of inoculating with modified germs, the new researches may 

 lead onwards to the discovery of dietetic or medical methods 

 of rendering men and other creatures unfit for the exhibition 

 of the virus of disease microbes. Two things seem pro- 

 bable : one, that of producing a state of constitution in 

 which the disease germs cannot grow at all ; the other, 

 that of compelling those that do grow to assume an 

 innocent f^rm. 



Besides reducing the virulence of disease microbes by 

 cultivating them in certain animals, some may have it 

 attenuated by growing them in the presence of free oxygen, 

 while to others of Pasteur's aiicrobic* family this gas is 

 fatal. Temperature is also an important element in deter- 

 mining the properties of microbes. M. Varigny, in a 

 paper on the.';e parasites, states that the malignant pustule 

 .sort does not grow in birds, because their temperature is 

 too high to suit it. Microbes, also, have their battle of life 

 against each other when their needs are the same. The 

 strongest then prevails, and it is fortunate when it is the 

 least mischievous. 



No microbe can be identified as the cause of a particular 

 disease unless that disease can be produced by inoculating 

 some animal with it. Koch's cholera bacillus is not be- 

 lieved in because it does not fulfil this condition. If the 

 able experimenter had not been acting as a State official 

 detective of the cholera poison, he would probably have 

 exhibited greater caution. 



A 



REMARKABLE LANDSLIP 



CAUSE. 



AND ITS 



AT the end of December, 1882, after several days' inces- 

 sant rain, the traffic on the Bellegarde and Geneva 

 branch of the Paris, Lyons, and Mediterranean Railway 

 was .stopped by slips on the hillsides of cnormnus dimen- 

 sions, which occurred near Fort de I'Ecluse, about seven 

 miles from the Swiss Frontier. At this point the line 

 following the right bank of the Rhone, and about 140 ft. 

 aliove it, passed through a tunnel about 160 ft. long, lined 

 with masonry, which was completely destroyed by the 



PLAN _ 



POST OE 

 L'ECLUSE 



APPROXIMA 



slipping of the hillside above it, the volume of material dis- 

 placed being estimated at about 1,250,000 cubic yards. As 

 the accident was evidently caused by an excessive increase of 

 ■subterranean waters and their overflow into the loose ground 

 of the hillside, it was decided to establish proper drainage 

 works as soon as the line had been temporarily restored. For 

 thelatter purpose the ground wascleared by blasting on a large 



* Ancrohic, growing without contact with air. The ferments 

 that grow in air Pasteur calls aerobics. 



