GENERAL PATHOLOGY 377 



Anatomically, similar changes in the cells, tissues and organs 

 correspond to similar pathological conditions. The same 

 changes in the blood as are evidenced by hyperaemia, hae- 

 morrhage and anaemia can be seen in all red-blooded animals 

 just as they are seen in man. 



The same thing is true with regard to the unorganised de- 

 posits (concretions, atheroma, fat), the formation of water and 

 gas, and especially organised new growths consisting of blood 

 vessels, muscle, nerve, glands, cartilage, bone, connective tissue, 

 epithelium, true skin, mucous membranes and serous mem- 

 branes; not to mention malignant new growths composed of 

 cells with or without intercellular substance, or connective 

 tissue stroma, and swellings due to tubercle or abscess 

 formation. 



Inflammation plays an important part in comparative 

 pathological anatomy, the well-known result of irritation which 

 causes a quantitative and qualitative increase in local metabolic 

 processes, and which varies according as the organ which is 

 attacked possesses a rich capillary network of its own between 

 the cells, or only experiences an influx of plasma as the result 

 of irritation. The inflammatory reaction often goes on to the 

 formation of pus-cells ; in other cases permanent new tissues 

 are formed (connective tissue, vascular tissue, bone, etc.), or a 

 degeneration of the cellular elements occurs. 



Pathological degeneration may take place, both in man and 

 animals, without any preceding inflammation. Tissues may 

 undergo fatty or granular degeneration, may become calcified 

 or pigmented, or may be converted into a mucous or cheesy 

 granular mass. 



Senile atrophic and degenerative changes occur in animals, 

 especially domesticated animals, as well as in man. 



Portions of the body may be destroyed by moist, or dry 

 gangrene, a process which in young persons is sometimes due 

 to extremes of temperature (freezing or burning), and some- 

 times to mechanical violence. 



When a man or animal dies the phenomena of dissolution 

 are identical in both cases : the skin becomes bloodless with 

 post-mortem lividity in the dependent parts; rigor mortis followed 

 by relaxation occurs ; fluid collects under the skin and within 



