REPARATIVE PROCESS GRANULATION. 355 



of them is chiefly dependent on the condition of the wound, as to seclu- 

 sion from air, or exposure to it. When the reparative effusion is 

 poured out into a subcutaneous wound, the " nucleated blastema" 

 appears to be gradually developed into fibrous tissue without any loss, 

 and usually with freedom from local inflammation (beyond what may 

 be the immediate result of the injury), as well as from constitutional 

 irritation. This process seems to take place naturally in cold-blooded 

 animals, even in superficial wounds ; the contact of air not producing 

 that disturbance in it, which it occasions in warm-blooded animals. 

 And Nature frequently endeavours (so to speak) to bring it about in 

 the superficial wounds of warm-blooded animals, by the formation of a 

 large scab, which protects the exposed surface ; but this happens much 

 less frequently in the Human subject, than it does among the lower 

 animals ; the unnatural conditions in which a large proportion of the 

 more civilized races habitually live (especially deficient purity of the 

 air, continual excess in diet, and the frequent abuse of stimulants), 

 being obviously unfavourable to it. The application of steam to 

 wounded surfaces has been found to favour the reparation by the most 

 healthy process ; and the formation of an artificial scab by means of 

 resinous unguents has also been practised with advantage. It is the 

 duty of the Surgeon to endeavour to promote it by every means in his 

 power ; since it is the method of healing, which is not merely the most 

 desirable as regards its economy of nutritive material and freedom 

 from constitutional irritation, but which most completely supplies the 

 loss of substance, so that the cicatrix does not contract. The newly- 

 formed fibrous tissue becomes vascular, by the extension of loops or 

 arches from the adjacent capillaries, and of other loops from these; 

 and subsequently other structures such as bone, lymphatics, and 

 nerves, may be developed in it. True Cartilaginous tissue, and the 

 higher form of Muscular fibre, however, seem never to be thus generated 

 de novo in the new tissues of a repaired part ; so that wounds of Carti- 

 lages and Muscles are united by simple fibrous texture. 



637. In an open wound, on the other hand, which is healing by the 

 process termed G-ranulation, the "nucleated blastema" is rapidly deve- 

 loped into cells, amongst which vessels speedily extend themselves ; but 

 the vitality of this tissue is very low, and that part of it which is ex- 

 posed to the air passes into the condition of pus ? its cells being either 

 imperfectly developed from the first, or speedily undergoing degenera- 

 tion. Thus there is a constant waste of plastic material, the amount of 

 which, in the case of an extensive suppurating sore, must be a serious 

 drain upon the system ; whilst at the same time, the local inflammation 

 is greater, and gives rise to more or less of constitutional disturbance ; 

 and the formation of new tissue is so much less complete, that by its 

 subsequent degeneration, and removal by absorption, a contracted cica- 

 trix is produced, which is different from the original texture. The new 

 tissue is here produced by a metamorphosis of cells into fibres ; and this 

 change is taking place in the deeper part of the granulation-structure, 

 whilst the more superficial is degenerating into pus. The difference 

 between the two modes of reparation now described, is often one of life 

 and death, especially in the case of large burns of the trunk in children; 



