372 THE ORGANS OF CIRCULATION. 



a number of different points, such as the submaxillary artery, on the 

 side of the lower jaw : in the case of very thin animals at the radial 

 within and in front of the elbow joint ; at the internal saphenous 

 artery, at the height of the mamma or scrotum ; or at the coccygeal 

 artery, at the base of the tail. 



This examination reveals the frequency (50 to 60 per minute), the 

 quality, whether strong, feeble, imperceptible, etc., the regularity, 

 etc., etc. 



Yeins. The veins are more easily examined than the arteries, on 

 account of their superficial position in most cases. 



Inspection and palpation are the only means of examination. 



Inspection shows the degree of fulness or collapse, and also the 

 existence or absence of what has been termed venous pulse. 



Venous pulse occurs only at the lower extremity of the jugulars. 

 It is very frequent in animals of the bovine species, and in thin animals 

 is not necessarily a pathological symptom. It is due to reflux of blood 

 in the anterior vena cava under the influence of the expiratory effort ; 

 sometimes to emphysema, tuberculosis, etc. ; in other cases to the 

 return of blood towards the vena cava and jugulars at the moment of 

 auricular systole, as a result of lesions of the tricuspid or auriculo- 

 ventricular orifices. 



By palpation of the veins their permeabilitj' can be estimated, also 

 the degree of distension or obstruction, and the condition of their 

 contents. 



Capillary system. Among methods of arriving at the state of the 

 circulatory system must be included an examination of the vascular con- 

 dition of the accessible mucous membranes, such as those of the eye, 

 mouth, nostril, vulva, etc. This examination is easy to carry out, 

 and is of value in diagnosing congestive states, pneumonia, and local 

 inflammation. 



Blood. Examination of the blood is sometimes necessary for the 

 exact diagnosis of certain diseases, and therefore should be carried out 

 whenever occasion requires. The physical state, coloration, and rapidity 

 of coagulation afford valuable data in certain diseased conditions, and 

 indicate the approximate richness in haemoglobin, the normal or ab- 

 normal composition of the plasma, and the richness of the blood in 

 white corpuscles. 



Microscopic examination is still more valuable, whether carried out 

 by the moist method, in which a drop of blood is compressed under a 

 cover glass, or the dry method with or without staining. In the latter 

 case the specimen is fixed with a mixture of equal parts of alcohol and 

 ether or by immersing it in a 1 per cent, solution of osmic acid. 



By this means it is possible to detect the condition of the red and 



