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in this way the disease could be passed on from animal to ani- 

 mal througli an indefinite series. In some animals the cocci 

 were found in the blood, and when this was the case well- 

 marked constitutional disturbance was observed. There are 

 some forms of abscesses known as cold chronic abscesses, which 

 do not contain cocci, and in twenty inoculations with matter 

 from these Odgston failed to develop either an abscess or con- 

 stitutional disturbance. There is, therefore, an obvious con- 

 nection between the micrococci and the infective properties 

 of the pus. But Odgston carried his experiments further ; he 

 cultivated the micrococci outside the body. He made a small 

 hole in an egg, and by suitable means he introduced a drop of jdus 

 from an acute abscess into the end farthest from the hole. He 

 covered the opening with antiseptic dressing, and kept the egg 

 in an incubator at 98° temperature during ten days. The egg re- 

 mained sweet and fresh, but chains of micrococci were found in 

 the albumen. A drop of this albumen was injected into an 

 animal's back. An abscess was formed, and numerous micro- 

 cocci were found in the pus, and also in the blood of the animal. 

 These experiments were repeated, and varied by inoculating a 

 second egg from the first, and after inoculation of an animal 

 from this egg the same results were observed as in the first 

 experiment. 



Let us turn to another example — one of a more complicated 

 character. It has been known from the earliest history of 

 medicine that the injection into the tissues of a healthy body of 

 a small quantity of putrid matter is usually followed by 

 alarming and sometimes fatal consequences. Sometimes the 

 animal dies in a few hours ; in other cases there is a stage of 

 incubation, in which no symptoms show themselves. Then 

 comes fever, and after this either recovery or death. The 

 chemists and biologists have discovered that in putrid matter 

 there is a chemical compound (sepsin) which is an active poison, 

 and also numerous Bacteria. When an animal dies a few 

 hours after inoculation, he dies with symptoms of poisoning, and 

 no abnormal growths are found in the blood or tissues. But if 

 the animal escape the action of the poison, and dies afterwards 

 in the second mode I have described, then we find Bacteria in 

 most parts of the body. Koch's experiments on mice will serve 

 as an illustration. Koch injectecl five drops of putrid blood 

 into mice, and the animals died in from four to eight hours. 

 No Bacteria could be found in the blood, nor did the fresh 

 blood of the poisoned mouse produce any effect when injected 

 into another mouse. If a smaller quantity of the putrid blood 

 were injected the effects were different. Some mice escaped 

 without injury, but others became ill and died in from two to 

 three days. Kow mark the difference. The blood of these 



