12 BOVINE PATHOLOGY. 



liable to disorder, and very early indicates systemic 

 disease. It varies under diseased conditions in its 

 moisture and smoothness as well as temperature. We 

 see it dry and harsh, with an erected condition of its 

 hairs, ^' staring,^' as it is termed, in most disorders. It 

 may be bedewed with moisture, locally or generally, as a 

 result of pain. While coldness with dampness — " cold 

 sweats '' — are a sign of approaching dissolution. The 

 mucous membranes exhibit variations in conditions visible 

 to the eye, and thus serve to supplement the conclusions 

 arrived at from the state of the skin ; they become 

 reddened in fever, purple in certain morbid conditions of 

 the blood, pale in low fever and other debilitating con- 

 ditions. 



The various excreta should be most carefully examined 

 as to their quality, quantity, and mode of expulsion. 

 Each excretion has a definite normal composition as ex- 

 hibited by certain physical and chemical characters. 

 Odour, appearance (including colour, form, and arrange- 

 ment of components), consistence, and in some cases even 

 taste, exercise the special sense faculties of the observer. 

 Specific gravity is especially altered in the fluid matters 

 given off from the body, such as urine and milk ; it is 

 tested by modified forms of the hydrometer, or by sp. gr. 

 balls, which sink or float according to the density of the 

 liquid in which they are placed. The faeces and urine 

 should be subjected to physical and chemical tests. 

 Sweat, saliva, and especially milk should be likewise 

 examined. We shall hereafter note the special features 

 of various excreta and secretions as altered by disease. 

 Among other ejecta the expired air must not be forgotten ; 

 its odour often leads to diagnostic inferences. Micro- 

 scopical examination enables us to determine whether 

 those constituents of excreta which have a definite form 

 present their ordinary characters, and are in proper pro- 

 portion. The microscope is a most useful aid to diagnosis, 

 and as having a wide utility may be here mentioned. 

 Moderate powers, as the -J--inch and J -inch by good makers, 

 are sufficient for ordinary diagnostic purposes. The blood 



