THICK WIND.— BBOKBN WIND. 265 



mechanical nature, which causes in all cases origiaate in pre- 

 vious disease. 



Thick Wind arises from a portion of one or both of the 

 lungs being in £t state of permanent solidification : the solidified 

 portions of which constitute a mechanical obstacle to the proper 

 difiusion of air through the air cells of the tissues afiected; 

 or in other words, a portion of the lungs being permanently 

 solid, and the organs having the same quantity of labour to 

 perform as when they were perfect, the labour, in consequence, 

 is necessitated to be done with greater rapidity ; hence the 

 cause of the animal breathing so quickly, especially when 

 worked severely or driven too fast ; also, why the derangement 

 in question is denominated Thick Wind. 



The origin of the pulmonary solidification arises in every 

 instance from inflammation having previously affected either 

 the substance of the lungs or the bronchial tubes, or both ; and 

 the parts affected are generally towards the posterior and 

 inferior borders of the organs. Sometimes they will be found 

 perfectly solid for four or five inches in breadth immediately 

 above the limits in question. 



If the solidified tissues are divided across the direction of 

 bronchial tubes, and the divided portions are examined with a 

 microscope of low power, the form of the smaller tubes is readily 

 seen ; but their cavities are completely plugged with solid lymph, 

 or a mixture consisting apparently of lymph and mucus. 



Beoken Wind. — The difficulty of breathing, which charac- 

 terises Broken Wind, originates' from an entirely different 

 cause ; it arises from what is called Emphysema of the lungs.* 

 or the presence of air between the substance of the lungs and 

 the serous or outer membrane which invests them. 



