lnjcctiotis .liiciifs. 65 



disease does not appear for a year. 'Jlie inllucnce exerted by 

 the virulence, the amount of toxine and the ])artieuhir infec- 

 tious germ u])(in the period of infection may he appreciated after 

 introduction of tetanus toxine into mice: the symptoms of the 

 disease, depending" upon the dosage, appearing after varying inter- 

 vals from 12 hours to 2 — 6 days. 



The (lisscmiiiaUoii and nniltiplicafioii of pafluii^ciiic i^cniis in 

 tJic body exhibit a number of peculiarities. .Some micro-organ- 

 isms remain closelv confined to the immediate vicinity of the 

 point of infection, giving rise from this localizetl situation tcj toxic 

 results in proportion to their own disintegration and to the ab- 

 straction by the fluids of the body of their toxic substances. Thus 

 they may cause lesions only in the neighboring tissues or induce 

 intense general disturbance after absorption. The tetanus bacillus, 



ft 



for example, does not grow free in the body (except in the uter- 

 ine cavity, where, under anaerobic conditions, the organism can 

 accumulate in large quantities after having once lieen introduced) ; 

 in the course of a dav or two after inoculation it can no lonsrer 

 be found at the site of infection (wound), nor elsewhere in the 

 body. It disappears because of its disintegration and through the 

 agency of the phagocytes. Its toxine, however, is absorbed and 

 causes the ganglion cells to undergo necrobiotic changes. Often 

 bacteria, as the pyogenic organisms, increase b\ multiplication at 

 the site of infection, but are prevented from further extension by 

 the defensive properties of the body. 



For the most part the germs are distributed from the point of 

 infection along tlic lymph channels, in part at least because the 

 newly developed germs are produced about the borders of the focus, 

 are swept away in the lymph plasma or are taken up by the leuco- 

 cytes and carried elsewhere. The local focus (local infcctio)i) en- 

 larges directly into the surrounding regions (regional infection) ; 

 and the microbes, conveyed by way of the lymph channels, are car- 

 ried deep into the tissues to the lymph glands, from one site to an- 

 other, from one lymph gland to another, until they finally reach 

 the blood. They ma}- also gain direct entrance into the capillaries, 

 veins and arteries from the point of infection (as in wounds or 

 ulcers, or by direct extension by growth through the vessel walls) 

 and be carried along with the blood current (embolic or hcemato- 

 gcnous infection). There thus are produced at a distance from 

 the point of entrance or primary focus of infection new deposits 

 of the infectious agents : and either new local areas of disease,, 



