CANCER GERMS. 177 



the great vascularity of the organ, the slowness with 

 which the blood, already retarded by passing through 

 a complicated system of capillary vessels, traversing 

 the dense plexus of vessels that goes to form its lobular 

 substance a cause unquestionably favourable to such 

 a result. Moreover we well know that the liver is the 

 grand sentinel or "floodgate" through which the 

 whole blood returning from the lower extremities and 

 intestines must pass before it gets to the great centre 

 of circulation and purification the heart and lungs. 

 Bearing this in mind, we can readily perceive how, 

 when the stomach or intestines become ulcerated, the 

 blood that flows to and through the liver from these 

 parts is liable to be contaminated by pus, and other 

 noxious aliments, setting up inflammation which 

 quickly terminates in abscess. How ? When the 

 stomach is the seat of cancer the portal blood is liable 

 to be contaminated by cancer germs, which bi-.in.LT 

 stopped in their passage through the liver, are these 

 deposited and developed into " cancerous tumours." 

 In such cases the abscesses and the secondary cancerous 

 tumours are usually found only in the liver, which 

 seems to detain all the pus globules and cancer germs 

 that are brought to it by the portal blood ; and it rarely 

 happens, under such circumstances, that any of these 

 germs of mischief pass through to cause abscesses or 

 cancerous tumours in the lungs or other organs of the 

 body. There are four varieties of cancer (carcinoma) 

 found in the liver, each having its peculiar character- 

 istics, which we will now briefly examine in succession. 

 1. THK MKDULLARY CANCER. This is the most com- 

 mon form of cancer found in the liver. It occurs either 



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