NON-INFLAMMATORY TORMATIONS. 327 



wliicli the pleura lias been converted must and will contract just 

 as a urinary bladder contracts. And this contraction occurs 

 with such force that not only are the soft and yielding thoracic 

 organs compelled to follow it, but the ribs also are dragged 

 downwards and inwards till they overlap one another like the 

 tiles on a roof; the vertebral column itself undergoing a corres- 

 ponding curvature. At the same time, the size of the cavity is 

 proportionately lessened ; a few drops only of pus occasionally 

 dribble from the fistulous orifice. And the process of repair is 

 brought to a close by the total obliteration of the cavity. 



B. ISTOX-IXFLAMMATOEY FORMATIONS. 



§ 279. Were I in this place to consider all the cancerous, 

 sarcomatous, chondromatous and lipomatous affections which are 

 occasionally met w^ith in serous membranes, I should be obliged, 

 not only to recapitulate what has already been laid down con- 

 cerning morbid growths in general, but to anticipate in great 

 measure the diseases of the alimentary canal, the lungs, liver, &c. 

 For the serous coat of any organ stands simply in the relation of 

 adjacent connective tissue towards those heteroplastic growths 

 which have their origin and seat in the parenchyma of the organ 

 itself; and it is in this capacity that it shares in the neoplastic 

 process. The present chapter will therefore be restricted to the 

 consideration of such growths as originate primarily in the 

 serous membranes and run their course mainly within their paren- 

 chyma. 



§ 280. Foremost among these stands that overgrowth of con- 

 nective tissue which occurs in the -svalls of a serous sac during 

 the continuance of a chronic dropsical effusion. The first stage 

 of the process presents itself to our eyes as a milky cloudiness of 

 the membrane. This is partly due to a moderate degree of 

 thickening, but mainly to an alteration in the consistency of 

 its fibres. Vircliow has given the name of " sclerosis " to 

 that condition of the fibres of connective tissue, in which 

 their bulk is but little altered, while their solid contents (i.e. 

 their density) are considerably increased. Such fibres are stifFer 

 tlian usual ; they are less capable of swelling by imbibition ; they 

 are, upon the whole, more indifferent to reagents, and refract light 



