464 THE SOLIDS. 



petechias are of irregular form, and of much larger size than the Mal- 

 pighian bodies have ever been observed to acquire. He gives, also, a 

 figure representing the occurrence of a similar appearance, from artificial 

 injection, at the surface of the kidney. In this figure the loops or 

 knuckles of the tubuli are seen filled with injection, presenting them- 

 selves at the surface, and surrounded by the venous network." 



The correctness of this explanation cannot be doubted ; and it is 

 therefore evident that the occurrence of these petechiae must be con- 

 sidered as invariably morbid. 



The anaemic condition of the kidney, when the result of disease, is 

 generally accompanied by increase in the size of the tubes from contained 

 secretion ; and it is the pressure of these on the surrounding vessels that 

 occasions their empty condition, and, in some instances, even obliteration. 

 The vessels of the Malpighian tufts likewise become involved, and the 

 Malpighian corpuscles themselves, thereby altered in form, from being 

 globular they become angular and compressed. 



Under the heading " Congestion followed by permanent obliteration of 

 the Capillaries," Dr. Gairdner has described a lesion of the kidney, which 

 he has designated by the term " waxy degeneration" in contradistinction 

 to the "fatty degeneration" 



" The appearances most characteristic to the naked eye of this form of 

 lesion, are those so admirably figured and described by Rayer as the 

 second form of his * nephrite albumineuse.' The kidneys are generally 

 increased in size, sometimes very remarkably so. Their consistence 

 varies : they are sometimes more flaccid than in the natural condition, 

 but always preserve considerable tenacity. The surface is either quite 

 smooth, or more or less depressed and furrowed. The venous vascu- 

 larity assumes, to a considerable extent, the stellate form ; the polygons 

 are mostly absent ; and the extreme irregularity and abruptness of dis- 

 tribution of the superficial veins gives to the surface a variegated or 

 ' marbled ' appearance, which is quite characteristic of this stage of the 

 affection. (See Rayer, Plate VI. figs. 2, 3. 5 ; Bright, Plate II. fig. 1.) 

 Occasionally, also, amid this unequal injection, there are to be found 

 scattered petechiae, indicating recent extravasations of blood into the 

 tubes. On section, the cortical substance has considerable volume, and 

 presents a smooth, glistening, almost semi-transparent appearance, which 

 cannot be better distinguished than by the term waxy. It may partake 

 in a slighter degree of the variegated character of the surface ; more com- 

 monly it is of uniform appearance, and of a yellowish or fawn colour, 

 sometimes verging into a pale flesh tint. The vascular strias of the cor- 

 tical substance are generally to be traced by a more or less distinct in- 

 jection, and a few injected Malpighian bodies, or petechise of extrava- 

 sation, are sometimes dispersed through the section. (See Rayer, Plate X. 

 fig. 3.) In other cases, a little further advanced, both the strise and the 

 Malpighian bodies are nearly destitute of blood. (Rayer, Plate X. fig. 1 ; 

 Bright, Plate Tl.fg. 1.) The pyramids frequently retain their normal 



