NATURE OF THE DISEASE. 47 



is for our present purpose sufficient to know that tliese are as 

 yet undetermined; the specific action, it would appear, is 

 exhibited, developed, or brought to maturity in connection 

 Avith particular organs, structures, and tissues. As to the 

 frequency of its location and apparent severity of action, this 

 specific poison shows marked and steadily distinctive prefer- 

 ences. 



The mucous membrane of the nasal passages, the eyes, 

 throat, and upper air passages, are the situations and struc- 

 tures most frequently and regularly invaded. FolloAving these 

 in susceptibility, we notice the bronchi, the textures of the 

 lungs, and the pleuras, and in a smaller number of cases the 

 mucous membrane and structures of the alimentary canal and 

 its associated glands and secretory organs ; while in some 

 manifestations the force of the disease seems expended on 

 another class of structures — the serous and fibro-serous. 



When the agent or factor immediately acting in the pro- 

 duction of the disease is sufficiently potent to issue in the full 

 development of the pyrexial state, it will be found that in all 

 such well-marked accompanying fevers the type is inclined to 

 be remittent, with daily, or rather evening, exacerbations. 

 These exacerbations are maintained throughout the course of 

 the disease, which in the ordinary catarrhal form is of very 

 variable duration, until perfect defervescence is established, 

 which is usually not suddenly, but gradually by lysis. 



From the mode in which influenza is spread and de- 

 veloped over vast tracts of countries, as also from the forms ot 

 seizures observed in men and animals, together Avith the 

 organs and textures specially involved, and the symptoms 

 which all animals exhibit, it has been concluded that in its 

 intrinsic nature influenza is closely allied, if not identical, in 

 men and animals ; hoAvever, the diftercnces in the structural 

 changes occurring during the progress of the disease in the 

 horse, as also the general severity of the symptoms, and the 

 larger percentage of fatal results, seem to indicate that this 

 particular blood- contamination in this animal is not identical 

 Avith that Avhich is encountered in man. It is indeed highly 

 probable that the organisms, if Ave accept the immediately 

 inducing agencies as of this nature, possess in each indi\ddual 

 species an individuality and specific distinctness for each 



