228 THE INFECTIOUS DISEASES. 



other bacteria, may induce local changes by means of its proteid constit- 

 uents which are set free as the organisms disintegrate after their death 

 in the body. ' 



PRIMARY CHARACTERISTIC LESIONS. 



We shall first consider the lesions which are most common and char- 

 acteristic of typhoid fever. 



The Intestine^. The lesions of the intestines consjgt of an inflnnjup- 

 torv enlargement ( hyperplasia) of the solitary lymph-nodules and of the 

 agminated Jymph-iio(Tulos*(Peyer's_patc]ie>^ > . ^Necrosis'" of* the nodules 

 with ulcer^ion frequently I < >1 i ows tne fryperplasia. 



The process appeal's to beghi^vith a catarrhal inflammation of the 

 mucous membrane, accompanied or immediately followed by changes in 

 the lymph-nodules. The lesions in the lymph-nodules begin early ; they 

 have been observed in persons who have died forty-seven hours after the 

 commencement of the disease. The increase in size of the agminated and 

 solitary nodules may be rapid or gradual. The nodules may be only 

 slightly enlarged, or may project far into the lumen of the intestine. 

 The enlargement is usually more marked in the agmiuated than in the 

 solitary nodules. Usually the whole of a Peyer's patch is enlarged, but 

 sometimes only a part of it. If the enlargement be gradual the different 

 nodules w r hich make up a Peyer's patch may enlarge, while the septa 

 between them remain but little changed, thus giving the patch an uneven 

 appearance- 



The patches which are only moderately enlarged are of reddish or 



Fir,. 109.- HYPERPLASIA OK PKYER'S PATCHES ix TYPHOID FEVER. 



reddish-gray color, are soft and spongy, and their edges blend gradually 

 with the adjoining mucous membrane. The patches which are more 

 markedly affected are of grayish color, of firm consistence, and rise 

 abruptly from the surrounding mucous membrane (Fig. 109) or even 

 overhang it like a mushroom. The largest patches are snipfttjjyaiR more 

 than three-eighths of an inch thick. 



1 For a study of the typhoid bacillus with reference to the pathology, diagnosis, 

 and hygiene of the disease, see llisx, Mcd. News, May llth, 1901. 



