CAKCINOMATA. 457 



with a tolerably soft variety of squamous epithelioma, which 

 differs from that of the tongue in its tendency to develope 

 papillary outgrowths. In the substratum of the laryngeal 

 mucous membrane, the tumour meets with a soil as ill-adapted 

 as possible for any extension by way of infiltration. Next to a 

 submucous layer made up of perfectly inelastic fibres, comes 

 one of fibroid tissue ; beneath this, and throughout the whole of 

 the submucous and mucous layers, networks of elastic fibres are 

 abundantly distributed. What wonder then if the growth tend 

 rather to extend outwards, to form papillary excrescences, for 

 years and years before it penetrates into the deeper structures 

 of the neck ? 



§ 327. In the cesophagus, a hard squamous epithelioma 

 gives rise, first to a zonular tumour, and then to a zonular ulcer 

 with an infiltrated base and edges ; the ulcer extends ; the 

 mucous membrane may come to be deficient all round the tube 

 for a width of two to three inches ; while the base of the ulcer 

 may invade, and eat its way into, the neighbouring air-passages 

 from without. A perforation through the floor of the ulcer 

 into the respiratory passages is a very grave accident. This 

 abnormal communication between the alimentary canal and 

 the respiratory passages is usually situated, n'ot in the trachea, 

 but in the posterior wall of the left bronchus. The left bronchus, 

 as is well known, crosses the oesophagus in its middle third, and 

 this is the point usually selected by oesophageal cancer. It has 

 justly been supposed that a mechanical cause of some kind must 

 contribute to localise the disease at this particular point ; and 

 that cause is to be sought in the fact that every morsel of con- 

 siderable size, in passing down the oesophagus, squeezes its 

 anterior wall against the posterior wall of the unyielding 

 bronchus. Of course perforation of the air-passages is only one 

 among many dangers to which the victim of oesoi^hageal cancer 

 is exposed. The zonular tumour may prove fatal by causing 

 stricture ; the extension of the morbid process to the mediasti- 

 mum may, during the inspiratory fall of tension in the thoracic 

 cavity, occasion the entrance of air from the oesophagus into the 

 lax areolar tissue which adjoins it, and so give rise to true 

 emphysema of the entire subcutaneous tissue ; the base of the 

 ulcer may become converted into a regular diverticulum, in 

 which the food may lodge and become decomposed, &c. 



