GENERAL DISEASES. 81 



' Blood dark ; petechise beneath the jDericardium, endo- 

 cardium, and pleurae. Intense staining of endocardium and 

 lining of the large vessels, and often a little blood-tinged 

 serum in the serous cavities, both soon after death, indi- 

 cating destruction of red corpuscles even during life ; intense 

 congestion and ecchymosis, with shedding of the epithelium 

 of the mucous membrane of the stomach and intestines ; 

 spleen swollen, soft and pulpy ; liver often swollen and con- 

 gested ' (Green). 



If now house-mice be inoculated with less quantity of 

 poison, the effect on the system will also be lessened. If a 

 drop or two only of the blood or meat infusion be injected 

 under the skin, many of the animals will show no untoward 

 symptom, while about a third of them will gradually sicken 

 and die. The symptoms thus manifested are : Dulness of 

 the eyes ; slow respiration ; great weakness and prostration; 

 and death occurs gradually in forty to sixty hours after 

 inoculation. After death there is slight oedema, sometimes 

 absent, at the place of inoculation, and the spleen is much 

 enlarged. 



Now, again, if a house-mouse be inoculated with a most 

 minute portion of the blood from one of the animals just 

 dead, the disease will be produced in it, and death will 

 ensue in less than two days. 



Now, this disease thus engendered is a septicsemia. But 

 it differs from the first-mentioned form of disease in beins: 

 intensely infective. 



The poison introduced gives rise to the disease by mul- 

 tiplying in the blood, and not by reason of its toxic proper- 

 ties, for it is in too small amount. 



A period also elapses between the time of inoculation — 

 the period of incubation — and the manifestation of symp- 

 toms, during which the germs multiply. This period may 

 be about twenty-four hours. 



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