CELLULAR TISSUE. 



513 



sidered how little is known respecting the real 

 structure of the Infusoria, Zoophytes, &c., and 

 when the numerous discoveries which have of 

 late years been made in these and much higher 

 animals, of parts whose existence was formerly 

 doubted or denied, are recollected, we shall be 

 inclined to think that there are special organs of 

 motion provided ; for it would be in direct oppo- 

 sition to the simple but constant laws observed 

 in the animal creation, were the organic tis- 

 sue, entitled the cellular, to acquire in the lower 

 classes a power of contraction, which in the 

 higher it does not possess, and which property 

 is the endowment of a totally distinct system of 

 organs, namely, the muscles. Whichsoever of 

 these opinions be correct, there is no doubt that 

 in the least perfect animals, a soft and gelatinous 

 matter, analogous to the cellular tissue, and 

 loaded with fluids, greatly predominates. As 

 we advance in the scale, it is found that organ- 

 ized substances of a diversified character are 

 developed in the nidus afforded by this cellular 

 texture, the proportion of which to the other 

 structures becomes thus diminished. 



MORBID CONDITIONS OF THE CELLULAR 

 TISSUE. As the cellular membrane is so in- 

 timately united with all other organs, it is very 

 liable to be involved in diseases commencing 

 in these parts ; but morbid action also very 

 frequently arises primarily in this tissue. It 

 is subject to 1, inflammation, acute and chro- 

 nic, circumscribed and diffused; to the effects 

 of inflammation, thickening and induration, 

 suppuration, ulceration, and mortification; 2, in- 

 filtration of blood, serum, air, and occasionally 

 of other substances, as urine ; 3, induration, 

 occurring in new-born infants ; 4, morbid 

 growths, such as fibrous productions, cysts, 

 melanosis,scirrhus, vascular sarcoma; 5, foreign 

 bodies ; 6, preternatural increase or hypertro- 

 phy, and degeneration, or atrophy. 



I. INFLAMMATION. This tissue is very fre- 

 quently affected by inflammation, which may 

 either present itself under the form of a distinct 

 affection, as when it attacks the subcutaneous 

 cellular membrane especially, or it may occur 

 as a part of some other disease, as when inflam- 

 mation of the parenchyma of the lungs, liver, 

 &c., spreads to the cellular tissue in which this 

 substance is universally involved. 



a. Acute circiunscribed inflammation, orpJileg- 

 mon. The anatomical characters of this form 

 of inflammation of the cellular substance are 

 essentially the same in whatever part of the 

 body it may arise, either in the subcutaneous 

 tissue, or in that part which penetrates into the 

 interior of the various organs ; it will, therefore, 

 be proper to trace the effects of it in a general 

 manner. 



1. Congestion of the bloodvessels. The ef- 

 fects of irritation on the capillary vessels, in 

 which the phenomena of inflammation are prin- 

 cipally observed, may be beautifully seen with 

 the aid of a sufficiently powerful microscope in 

 the transparent membrane of the frog's foot. 

 After having familiarized the eye by watch- 

 ing the circulation for a short time, we shall 

 find that the first effect produced by the appli- 

 cation of an irritant is a distinct and evident 



acceleration of the blood's motion. I have not 

 been able to satisfy myself of that diminution 

 of the calibre of the vessels which is said by 

 some observers to accompany this acceleration. 

 If the irritation be repeated, or if its power in 

 the first instance were considerable, it will be 

 seen after a certain time that the capillary ves- 

 sels become dilated, that the blood moves more 

 slowly, and often that it oscillates and circulates 

 apparently with difficulty ; its constituent parts 

 become less distinct, the particles being crowded 

 together. If the effects of the irritation now 

 subside, the dilated vessels contract and recover 

 their proper calibre, the blood again moves 

 more freely, and the circulation regains its 

 natural state ; but, on the contrary, if the mor- 

 bid action still persists, the membrane begins 

 to grow opaque, either in consequence of the 

 engorgement of the vessels, or, as it has appeared 

 to me, from an extravasation of one or other of 

 the constituents of the blood ; or, lastly, the 

 circulation altogether ceases, the vessels are 

 further enlarged, the blood is stagnant, and is 

 evidently deteriorated in quality, and the colour 

 becoming deeper and deeper, is at length per- 

 fectly brown, or even black. This is the order 

 in which the phenomena in the derangement of 

 the circulation occur ; and although they have 

 been more particularly studied in microscopical 

 observations on the lower animals, yet many of 

 them are daily to be observed in the human 

 body during the progress of inflammation. 

 Whilst the inflammatory action is confined to 

 the first of the above stages, in which there is 

 merely a preternatural excitement of the circu- 

 lation, it may be arrested and put an end to 

 without any further morbid change; and this 

 may even happen in the second stage, where 

 the blood, although accumulated and retarded 

 in its motion, still circulates in its proper ves- 

 sels. This speedy termination of the disease 

 has been called by the French writers deli- 

 tescence. 



2. Effusion. When the bloodvessels are 

 greatly congested and dilated, it usually hap- 

 pens that a part of their contents escapes, and the 

 cellular tissue becomes loaded with coagulable 

 lymph, more or less tinged with blood accord- 

 ing to the vascularity of the affected part, pro- 

 ducing that condition which has been called 

 red induration. This substance, by agglutina- 

 ting together the fibres and layers, causes the 

 hardness which is so perceptible on pressing 

 the diseased part. At the same time that this 

 solid deposition takes place in the centre, it is 

 found that the circumference of the inflamed 

 part is soft and oedematous, in consequence of 

 the cells being distended with a fluid which 

 appears to be the serum of the blood. Although 

 the cellular tissue is rendered more firm to the 

 touch by the effusion of lymph, yet, as happens 

 in the other organized structures of the body 

 when attacked by acute inflammation, the co- 

 hesion of its fibres is diminished, and it is, con- 

 sequently, more easily torn than in its natural 

 state, and its elasticity is also greatly impaired. 

 The preceding changes may be very beautifully 

 observed in the progress of pneumonia, when 

 the substance of the lungs is passing into that 



