62 CHEMICAL COMPONENTS OP THE HUMAN BODY. 



are subsequently penetrated by bloodvessels, and become regularly organized 

 tissues ; whilst those proceeding from the blood of cachectic subjects frequently 

 undergo a certain degree of organization with great rapidity, but do not go on 

 to the same perfection, and speedily degenerate. 1 



28. One of the most remarkable examples of the consolidation of a fibrinous 

 exudation into a regular fibrous tissue (which, however, never becomes vascu- 

 lar), is afforded by the membrane adherent to the interior of the egg-shell (mem- 

 brana putaminis), and also by that which forms the basis of the egg-shell itself 

 (Fig. 3). Between the two, there is no essential difference ; as may be seen 

 by examining " an egg without shell," as it is commonly termed (or rather one 

 in which the shell-membrane has not been consolidated by the deposition of cal- 

 careous matter) ; or by treating the egg-shell with dilute acid, so as to remove 

 the particles of carbonate of lime, which are deposited in the interstices of the 



network. The place of the shell is then found to 

 be occupied by a membrane of considerable firmness, 

 closely resembling that which lines the shell and sur- 

 rounds the albumen of the egg, but thicker and more 

 spongy. After maceration for a few days, either of 

 these membranes may be separated into a number of 

 laminae; each of which (if sufficiently thin) will show 

 a beautiful arrangement of reticulated fibres. It is 

 impossible to refuse to such a structure the designa- 

 tion of an organized tissue, although it contains no 

 vessels, and must be found by the simple consolida- 

 tion of a fibrinous exudation, poured out from the 

 lining membrane of the oviduct of the bird, so as to 

 Fibrous membrane from the Egg- invest and inclose the albuminous exudations which 

 gheii. have been previously poured out, layer by layer, 



around the yolk-bag. It is probably in the same 



manner that the Chorion of the Mammiferous animal originates ; since this is a 

 new envelope, formed around the ovum, during its passage along the Fallopian 

 tube. In the latter, for an ulterior purpose, vessels are afterwards developed, by 

 extension from the contained ovum ; and by the nutrition they supply, its size 

 is increased, and changes take place in its texture. But in the egg-membrane of 

 the Bird, there is no need of vessels ; because no subsequent change in its tex- 

 ture is required, and its duration is sufficient for the purpose it has to answer. 



29. Thus, then, we are led to regard the fibrillation of Fibrin as a process 

 quite different from the coagulation of Albumen or Casein ; and to consider it 

 as an expression or manifestation of the vital force with which the former has 

 been endowed, during that Assimilation of the crude material furnished by the 

 latter, which seems to be the first step in its conversion into living tissue. And 

 this view is confirmed by many facts, which will be more appropriately stated 

 when the Blood is under consideration (CHAP. IV.), and which show that the 

 condition of the Fibrin in that fluid is intimately related to the vital powers of 

 the system at large. When this fibrillation takes place out of the body, it may 

 probably be regarded as the ultimate manifestation of the vitality of the Fibrin, 

 which is expended in producing it; and .thus it happens that the fibrinous coagu- 

 lum passes into decomposition, without attaining any higher grade of develop- 

 ment. But when it takes place in contact with a living surface, the exuded 

 material, continuing to receive vital influence from this, and becoming pene- 



1 See especially Mr. Dalrymple's Memoirs " On the rapid organization of Lymph in 

 Cachexia," in the "Med.-Chir. Trans." vol. xxiii.; and "On the early organization of 

 coagula and mixed fibrinous effusions under certain conditions of the system," op. cit 

 vol. xxvii. 



