84 MICRO-ORGANISMS AND DISEASE. [CHAP. 



oedema is found at the seat of inoculation ; the spleen is large ; 

 in the oedematous tissue and in the blood-vessels, large and 

 small, numbers of minute bacilli are found, chiefly contained 

 in the white blood-corpuscles, but also free. They are very 

 minute, about O'OOOS to 0001 mm. long, to O'OOOl to 0*0002 

 mm. thick, isolated or in couples, or in chains of four or more. 

 The smallest quantity of this blood invariably kills, with the 

 same symptoms, house mice and sparrows, but not field mice. 

 Rabbits inoculated with these bacilli in the skin of the ear or the 

 cornea show only a local inflammation, and the tissues presently 

 contain numerous bacilli of the same kind. Such animals, 



FIG. 49. FROM A SECTION THROUGH THE SMALL INTESTINE OF A MOUSE DEAD 

 OF SEPTICAEMIA. 



The figure represents a section through a small vein in the submucous tissue, 

 filled with blood. At 1, there is a homogeneous substance and in it numerous 

 bacilli, but these bacilli are much larger than the bacilli of Koch's septicaemia 

 in the mouse. 

 Magnifying power about 700. (Stained with methylene blue and vesuvin.) 



after the local effect has passed off, are protected against any 

 further attack by the same bacilli. Koch cultivated these 

 bacilli artificially on mixtures of aqueous humour and gelatine, 

 of gelatine and peptone (1 per cent.), salt (0'6 per cent. NaCl), 

 and sodium phosphate in sufficient quantity to produce a just 

 alkaline reaction. The bacilli grow well on this mixture, and 

 by repeated and rapid division form peculiar branched series. 



(&) Bacillus of septiccemia of man. In several cases of 

 human septicaemia I have found in the blood-vessels of the 

 swollen lymphatic glands large numbers of minute bacilli, 



of the mucous membrane of the stomach and intestine, large numbers of bacilli 

 are occasionally found on the surface of the inflamed parts, and gradually 

 invading the inflamed tissue. Von Recklinghausen (Virchow's Archiv, vol. 

 xxx.), von Wahl (ibidem, vol. xli.), saw minute pustular nodules in the 

 inflamed gastric mucous membrane which were full of bacilli. Whether the 

 presence and growth of these bacilli was the primary cause or only a concomitant 

 symptom (due, for example, to the loss of active vitality of the tissue) remains to 

 be proved. 



