ABNORMAL FORMS OF NUTRITIVE PROCESS. INFLAMMATION. 573 



of Tubercles in the lungs and other organs, when it occurs as a kind of meta- 

 morphosis of the ordinary Nutritive process ; and in this manner it may proceed 

 insidiously for a long period, so that a large part of the tissue of the lungs shall 

 be replaced by tubercular deposit, without any other ostensible sign than an in- 

 creasing difficulty of respiration. In the different forms of tubercular deposit, 

 we see the gradation most strikingly displayed, between the plastic and the 

 aplastic formations. In the semi-transparent, miliary, gray, and tough yellow 

 forms of Tubercle, we find traces of organization in the form of cells and fibres, 

 more or less obvious ; these being sometimes almost as perfectly formed as those 

 of plastic lymph, at least on the superficial part of the deposit, which is in im- 

 mediate relation with the living structures around ; and sometimes so degene- 

 rated, as scarcely to be distinguishable. In no instances do such deposits ever 

 undergo further organization ; and therefore they must be regarded as caco-plastic. 

 But in the opaque, crude, or yellow Tubercle, we do not find even these traces 

 of definite structure ; for the matter of which it consists is altogether granular, 

 more resembling that which we find in an albuminous coagulum. The larger 

 the proportion of this kind of matter in a tubercular deposit, the more i it prone 

 to soften, whilst the semi-organized tubercle has more tendency to contraction. 

 This is entirely aplastic. It may be questioned, however, whether Tubercular 

 matter is not always, even in its most amorphous state, a product of cell-forma- 

 tion ; and whether the difference between the amount of organization which its 

 several forms present, is not due rather to a variation in the degree of its sub- 

 sequent degeneration than to an original diversity in histological condition. On 

 this view, Tubercle is to be considered as a formation sui generis, whose pro- 

 duction is dependent upon a special taint in the blood; and just as -the normal 

 lymph-products vary greatly in their degree of vitality, so that some undergo a 

 progressive and others a retrograde metamorphosis, so may tubercular deposits 

 either retain their original characters more or less completely (though never 

 advancing towards a higher character), or may undergo a very early and complete 

 degeneration. 1 Now although Tubercular matter may be slowly and insidiously 

 deposited, by a kind of degradation of the ordinary Nutritive process, yet it 

 cannot be doubted that Inflammation has a great tendency to favor it ; so that 

 a larger quantity may be produced in the lungs, after a Pneumonia has existed 

 for a day or two, than it would have required years to generate in the previous 

 mode. But the character of the deposit still remains the same ; and its relation 

 to the plastic element of the blood is shown by the interesting fact, of no unfre- 

 quent occurrence that, in a Pneumonia affecting a tuberculous subject, plastic 

 lymph is often thrown out in one part, whilst tubercular matter is deposited in 

 another. Now Inflammation, producing a rapid deposition of tubercular matter, 

 is peculiarly liable to arise in organs, which have been previously affected with 

 chronic tubercular deposits, by an impairment of the process of textural Nutri- 

 tion ; for these deposits, acting like foreign bodies, may of themselves become 

 sources of irritation ; and the perversion of the structure and functions of the 

 part renders it peculiarly susceptible of the influence of external morbific causes. 

 616. We frequently meet with abnormal growths of a Fatty, Cartilaginous, 

 Fibrous, or even Bony structure; which result from the development of these 

 tissues in unusual situations, and appear to originate in some perverted action 

 of the parts themselves ( 597). But there is another remarkable form of dis- 

 ordered Nutrition, which is concerned in producing what have been termed 

 heterologous growths ; that is, masses of tissue that differ in character from any 

 which is normally present in the body. Most of these are included under the 

 general designation of Cancerous or Fungous structures; and it has been shown 



1 See Mr. Paget in the " Pathological Catalogue of the Hunterian Museum," vol. i. p. 

 134; also Dr. Madden's " Thoughts on Pulmonary Consumption." 



