GENERAL ANATOMICAL CHARACTERS OF INFLUENZA. 65 



Thus it is that in instances where the inducing factor seems 

 the most powerful, where the amount and strength of the virus 

 implanted in the animal seem to have been most potent, seeing 

 it is struck do^vn at the very outset, ere even a good and com- 

 plete chain of well-developed symptoms is estabhshed, we often 

 meet with the least characteristic and distinctly marked morbid 

 lesions understood to be diagnostic of the disease. It is a fact 

 pretty well established by recorded observation that in other 

 diseases of a similar character, as well as in influenza, the most 

 distinctly marked and characteristic changes, those most typical 

 of the disease in any form, are to be observed, not in the ones 

 which have succumbed at once to the attack, but in such as 

 have steadily passed through its different stages, and have 

 only yielded after a long and determined struggle with the 

 disease. 



In the greater number of the cases of influenza exhibiting 

 distinct pyrexial features together with more or less imphcation 

 in the diseased action of the organs of respiration, the most 

 generally exhibited changes are seen in connection with these 

 organs. The fauces, with larjmx and pharynx, are much tume- 

 fied from infiltration of the submucous tissue, the membrane 

 itself varying in colour from a dark red to a livid gangrenous 

 appearance. The inner tracheal surface similarly coloured, 

 the markings disposed in streaks or irregularly formed and 

 distributed patches ; the bronchi the same, and filled with 

 frothy mucus occasionally of a rusty colour. 



Within the thorax, the alterations observable are in accord- 

 ance with the severity of the attack and its partiality for 

 particular structures. 



In many instances the intimate lung-tissue is not much 

 involved ; and when divided with the knife, nothing abnormal 

 may be noticed with the unaided vision, with the exception 

 that the minute bronchi may be filled with frothy spume, and 

 the general pulmonary tissue somewhat heightened in colour. 

 There may, however, even when the lungs themselves do not 

 exhibit much change, be very distinctive alterations in con- 

 nection with the covering of these organs and the walls of the 

 chest. 



Such changes generally range from heightening in colour, 

 the result of engorgement of the vessels of the pleural mem- 



5 



