604 OF NUTRITION. 



the most superficial of the Exudation-corpuscles, which are exposed to the 

 contact of air, change their character (in the mode to be presently described, 

 805), and become Pus-Globules ; whilst those in close contact with the sub- 

 jacent surface take a share in the process of reparation. A new layer of 

 exudation-corpuscles is next deposited over this : of which the outer portion 

 degenerates as before into pus-globules, whilst the inner part gives origin to 

 a kind of areolar tissue, forming Granulations. These Granulations are them- 

 selves extremely vascular ; and, as recently shown by Mr. Liston,* the ves- 

 sels of the subjacent tissue are much enlarged, and assume a varicose charac- 

 ter. The bright red colour of the Granulations, however, does not depend 

 on their vascularity alone ; for 'the cells themselves, especially those most 

 recently evolved, are of nearly as deep a colour as the blood-globules ; and 

 the superficial bleeding which follows even the slightest touch of the granu- 

 lating surface, does not proceed from blood shed from the newly-formed vessels 

 only ; for the red fluid shed in this manner contains, besides blood-discs, 

 newly-developed red cells, ruddy cytoblasts, pale granules and reddish serum. 

 It is a common property of animal cytoblasts, that they present a red colour 

 on their first formation, when in contact with oxygen ; but this hue they 

 lose again, whether they advance to perfect development and become integral 

 parts of a living tissue, or die and degenerate. 



801. The process of Granulation and Suppuration appears to differ from 

 that of simple Reparation (the modelling process of Dr. Macartney) in this, 

 that a large part of the Exudation-corpuscles deposited on the wounded 

 surface degenerate into Pus in the former case, whilst none are thus wasted 

 in the latter ; but that the existence of Inflammation occasions a more co- 

 pious supply of Fibrine in the former case, and increases its tendency to be- 

 come organized ; the filling-up of a wound with Granulations being thus a 

 much more rapid process than that renewal of the completely-formed Tissues, 

 which may take place in the absence of Inflammation. The imperfect cha- 

 racter of the Granulation-structure is shown, by the almost complete disap- 

 pearance of it after the wound has closed over. The portion of it in immediate 

 contact with the subjacent tissue, however, 'appears to undergo a higher organi- 

 zation ; for it becomes the medium by which the Cicatrix is made to adhere 

 to the bottom of the wound. It is very liable to undergo changes which 

 end in its disintegration ; as is evident from the known tendency to re-open- 

 ing, in wounds that have been closed in this manner. 



3. Abnormal Forms of the Nutritive Process. 



802. Under the preceding head, we have considered the chief variations 

 in the degree of activity, that are witnessed in the ordinary or normal condi- 

 tions of the Nutritive process, that is, those conditions in which the pro- 

 ducts are adapted, by their similarity of character, to replace those which 

 have been removed by disintegration. But we have now to consider those 

 forms of this process, in which the products are abnormal, being different 

 from the tissues they ought to replace. We shall confine ourselves to a brief 

 examination of the two most important of these states ; that which is termed 

 Inflammation ; and that which gives rise to Tubercular deposit. The 

 former results from an excess of the plastic element in the blood ; the latter 

 from a depraved condition of it, whereby its plasticity is impaired or destroy- 

 ed. Notwithstanding all the attention which has been given to the state of 

 the vessels in Inflammation, a careful consideration of its phenomena, with the 

 light which recent investigations have thrown upon these, leads us to attach 



* Medicc-Chirurgical Transattions, vol. xxiii. 



