THICK WIND. BROKEN AVIND. 205 



as effects dependant for the most part upon causes of a meclaani- 



cal nature, whicli causes in all cases originate in previous 

 disease. 



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

 lungs being in a state of permanent solidification : the solidified 

 portions of which, constitute a mechanical obstacle to the proper 

 diffusion of air through the air cells of the tissues affected ^ 

 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 quicldy, 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 soHd lymph, 

 or a mixture consisting apparently of lymph and mucus. 



Beoken "Wind. — The dif&culty 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. 



* See Glossary. 



