INTRODUCTION 27 



in 1870-71. He not only saw, as others before him had 

 seen, that bacteria were present in diseases following infec- 

 tion of wounds, but described the manner in which the 

 organisms had gained entrance from the point of injury 

 to the internal organs and blood. He expressed the opinion 

 that the spherical and rod-shaped bodies which he saw in 

 the secretions of wounds were closely allied, and he gave to 

 them the designation " microsporon septicum." He believed 

 that the organisms gained access to the tissues round about 

 the point of injury both by the aid of the wandering leuko- 

 cytes and by being forced through the connective-tissue 

 lymph-spaces by the mechanical pressure of muscular 

 contraction. 



On erysipelatous inflammations secondary to injury 

 important investigations were also being made, Wilde, 

 Orth, von Recklinghausen, Lukomsky, Billroth, Ehrlich, 

 Fehleisen, and others agreeing that in these conditions 

 microorganisms could always be detected in the lymph 

 channels of the subcutaneous tissues; and through the 

 work of Oertel, Nassiloff, Classen, Letzerich, Klebs, and 

 Eberth the constant presence of bacteria in the diphtheritic 

 deposits at times seen on open wounds was established. 



. We see that the conception of a living, invisible some- 

 thing a contagium vivum was old, but by the use of the 

 rapidly improving compound microscope a host of investi- 

 gators was making this "something" more tangible; they 

 were describing various minute bodies seen in diseased 

 conditions that they believed to be living things, and to be 

 the cause of the conditions in which they were observed. 

 Yet no convincing demonstration of the relationship between 

 these supposed living foreign bodies and the diseases in which 

 they were present had been made. In 1855 Pollender 



