252 CIRCULATORY APPARATUS. 



numbers are e^-erywhere distributed between the lamellae ; here 

 and there we come upon larger aggregations of such cells. From 

 these nest-like deposits, as centres, new systems of concentric 

 lamellae of connective tissue originate, which are intercalated 

 between those already existing, thereby dissociating them from 

 one another. For the production of fibrous intercellular sub- 

 stance advances pari passu with the multiplication of corpuscular 

 elements ; the latter never preponderate to such an extent as to 

 make the products in any way resemble pus. We rather meet 

 w^ith scattered patches in which a soft, mucoid character of the 

 intercellular substance is associated with a retiform arrangement 

 of the cells — patches, therefore, of mucous tissue. Taking the 

 phenomena in their entirety however, we cannot but be struck 

 with the close similarity of the morbid products to the normal 

 texture of the intima ; hence we must regard the first stage of 

 the process, the so-called sclerosis of the intima, as an infamma- 

 tory overgrowth. 



§ 217. With this inflammatory overgrowth of the intima, 

 the process culminates. As often happens in the case of morbid 

 growth, time brings about a disproportion between the means of 

 supplying nourishment and the mass of material wdiich has to be 

 nourished. Tlie intima contains no vessels. It draws its pabu- 

 lum directly from the passing blood. The vasa vasorum, which 

 are never lacking in any of the greater vessels, barely j^enetrate 

 into the middle coat. Should the intima therefore become 

 thicker, those of its layers which are farthest removed from the 

 nutrient fluid, i.e. the outermost layers, those next to the middle 

 coat — will be the first to suff'er from lack of nourishment. And 

 here, two modes of retrograde tissue-metamorphosis may be 

 observed side by side. Tlie first and most extensive of these is 

 a fatty degemration of the cells, combined with solution of the 

 intercellular substance. The naked eye detects in the interior 

 of the hardened elevation, just upon the limits of the media, 

 opaque yellowish-white striae, running in a direction parallel to 

 that of the surface, and uniting to form a more equably yellow 

 spot. Should the morbid change be more advanced, this is re- 

 placed by a " focus of softening" of variable size, occupied by a 

 friable or greasy pulp of the same yellowish hue. The presence 

 of cholesterin crystals in large numbers gives this " atheromatous 

 pulp " a spangled lustre. Should the focus of softening have 



