10 BOVINE PATHOLOGY. 



neither of these organs being stimulated because o£ the 

 deficiency of oxygen. Inhalation of such heavy gases as 

 prevent access of oxygen to the lungs, suffocation, and 

 many other diseased conditions bring about death in this 

 way. Sometimes the expulsion of air from the lungs is 

 laboured, and accompanied by a harsh rattling sound ; the 

 breathing is then said to be Stertorous. It depends 

 upon the movement of velum pendulum palati by the 

 expiratory current, and may be observed in cases of 

 parturient apoplexy, for instance. 



Cough is brought about by a deep inspiration, the 

 glottis is then closed until the outward current of air 

 suddenly forces the vocal cords apart, when the air 

 escapes with a sharp sound, and emerges either through 

 the nostrils or mouth with some force, carrying with it any 

 foreign body, such as a mass of mucus, &c., which may 

 have been about the glottal opening. Cough depends upon 

 reflex nervous action, and may be primary when the 

 irritation exists in the lungs or air passages, or secondary, 

 when due to irritation of the stomach, intestines, or 

 other parts having nervous communications with the 

 respiratory apparatus. We speak of harsh, difficult, 

 paroxysmal, suppressed, and other coughs which do not 

 require special description. Some coughs are considered 

 pathognomonic signs, such as that of pleuro-pneumonia 

 zymotica. 



Oxygen introduced by the process of respiration into the 

 blood is the grand agent in the production of animal heat. It 

 combines with various matters, whether in the blood or in the 

 other tissues, and produces with them carbonic anhydride 

 and water (which are passed off by excretory organs, espe- 

 cially the lungs) and heat, which enables the several parts 

 of the body to perform their functions. Observation has 

 proved that for each species of animal we may determine a 

 standard internal temperature, which proves useful in 

 the diagnosis of disease, especially when of an epizootic 

 and contagious character; to a slight degree indi- 

 viduality modifies the readings. Though thermometry is 

 yet in its infancy many valuable results have been obtained 



