RELATION OF ORGANISMS TO DISEASE, Now, these facts that have been stated supply the foundation of the modern view of infection and contagion. The resemblance between fer mentations and putrefactions and various dis eases, specially those of an infectious or con tagious sort, had long ago been remarked; and if the one set of occurrences was the work of organisms or germs, why not the other? Why not? In 1850 a French doctor, Davaine, on examining with the microscope a drop of blood from a patient who had died of splenic fever, observed little thread-like bodies about twice the length of a blood corpuscle. He paid little heed to his discovery. But in 1863, excited by the proof Pasteur had meanwhile offered of organisms of a similar nature being the cause of various fermentations, he made new obser vations, and found the same thread-like body constantly present in the blood of sheep and rabbits dead of the disease. These are the first definite observations that link contagious dis eases to the life and growth of germs.
Now it so happens that about the same time ruin was threatened to one of the industries of France, that of silk culture, by the presence of a mysterio'tis disease among the silk-worms that spread like a plague not only in France, but in Spain and Italy as well. In 1865 the loss to France by its ravages amounted to over four million pounds sterling. In the distress the Government of France turned to Pasteur, who had taught the French wine-growers how to prevent disease in their vines, and besought him to render his assistance. He visited the affected districts, and was speedily able to affirm that the disease was due to the presence in the insects of minute cylindrical bodies about imlauth of an inch long, and therefore only discoverable by the microscope. These micro scopic organisms had been observed years before by an Italian naturalist, Filippi ; but whether they had any connection with the disease was not known. Pasteur proved they were the cause of the disease, and that it was contagious. He showed that if a silk-worm, in
whose body the round bodies were present, was pounded up with water in a mortar, and the poundings painted with a brush on the leaves on which healthy worms were fed, they would all without fail be smitten with the plague. For three years he worked at silk-worm dis ease, and succeeded, with grievous injury to his own health, in unearthing its precise nature and in devising means for its arrest, by the adoption of which prosperity was restored to this industry. During this time, and for some years after, a hot discussion had been going on about Davaine's discovery of bacilli in splenic fever. In 1876 a young physician living near Breslau, Dr. Koch, published a paper giving a full account of the life-history of the splenic fever bacillus, and a complete demonstration that its introduction into the body of animal or man was the only cause of the disease. In the following year (1877) Pasteur, driven into the question of contagious diseases by his experi ments on beer, wine, and silk-worm diseases, investigated the question, and confirmed and extended the results of Koch. Now, what of splenic fever? It may attack the horse, the cow, the sheep, and man. In some years France lost by it in cattle from a half to one million pounds sterling. It is rampant, not in France only, but in Spain, Italy, Russia, and Egypt It has appeared in this country, transported from Russia by hair. It is sometimes called wool Sailers' disease, because in this country it has been chiefly wool-sorters that have been at tacked by it. The evidence is conclusive that the hides had been those of animals dead of splenic fever. Some of the blood of the animal containing the germ that is the cause of the disease had soiled the skin, and the bacillus had produced spores. These seeds had clung to the hairs, and, in spite of drying, had retained their vitality. In the process of sorting they had been detached and had gained entrance to the bodies of the sorters by the air breathed.