456 OF NUTRITION. 



a means employed by Nature for the purpose, under the unfavourable circum- 

 stances of Irritation or a continuance of Inflammation ; proving that parts, 

 previously in a healthy state, are disposed to heal in despite of many impedi- 

 ments thrown in their way. The Granulation-structure is a special one, 

 formed for a temporary purpose. It is endowed with higher vascularity and 

 a more rapid power of growth, than is possessed by any modification of ordi- 

 nary tissue ; but it is very easily destroyed by injury, or by a higher degree 

 of inflammation. The existence of Granulations has been supposed to be 

 necessary to fill up deficiencies ; this, however, is not altogether true ; as we 

 occasionally find very considerable vacancies filled with lymph, which gra- 

 dually becomes organized, without being converted into granulations ; and the 

 void may be also supplied by the process of natural growth just described. 

 Moreover, it is only in the beginning that granulations take the place of the 

 natural structure ; for the approximation of the edges of a wound filled with 

 them, requires that they should be removed by interstitial absorption ; so that 

 wounds healed by this process do not exhibit any remains of the new medium. 

 This approximation somewhat resembles that which occurs in open wounds 

 that have never inflamed, being the result of the natural processes of growth, 

 and it does not take place until the Inflammation has in great degree subsided ; 

 but it differs from the modeling processes in this, that, as the wound is oc- 

 cupied by granulations, its closure takes place prematurely, as it were ; so 

 that, when the granulations are subsequently absorbed altogether, a contracted 

 cicatrix is the result. It will be presently seen, that the formation of the 

 Granulation-structure is intimately connected with the elaboration of Pus ; 

 and' this process, accompanied as it is with such great constitutional disturb- 

 ance, and involving such a loss of nutritious material, cannot but be regarded 

 as an action to be altogether avoided, if possible. 



601. We shall now consider, more in detail, the nature of the process of 

 Granulation, and of the Suppuration which usually accompanies it. Its com- 

 mencement is exactly conformable to the first stage of ordinary reunion by the 

 first intention ; for liquor sanguinis is thrown out, in \vhich exudation-corpus- 

 cles present themselves in large numbers. According to Gerber, the trans- 

 formation of these into a sort of imperfect Epithelium may be seen to take 

 place within half an hour. New layers are in the mean time developed, and 

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

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

 ( 609), and become Pus-Globules ; whilst those in close contact with the subja- 

 cent surface take a share in the process of reparation. A new layer of exuda- 

 tion-corpuscles is next deposited over this, of which the outer portion degene- 

 rates as before into pus-globules, whilst the inner part gives origin to a kind of 

 areolar tissue, forming Granulations. These Granulations are themselves ex- 

 tremely vascular ; and, as recently shown by Mr. Listen,* the vessels of the 

 subjacent tissue are much enlarged, and assume a varicose character. The 

 bright red colour of the Granulations, however, does not depend on their vas- 

 cularity alone ; for the cells themselves, especially those most recently evolved, 

 are of nearly as deep a colour as the blood-globules : and the superficial bleed- 

 ing which follows even the slightest touch of the granulating surface, does not 

 proceed from blood shed from the new-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 ad- 

 vance to perfect development and become integral parts of a living tissue, or 



* Medico-Chirurgical Transactions, vol. xxiii. 



