RKTRn(;R|.:ssi\'i': 'iissuic I'liANtiics. 2\1 



era! quantity of Lngol's solution for one or two minute;-., wash 

 the excess of the reagent off and the above color reaction will 

 be observed). The test is equally applicable to niacruscopic and 

 microscopic sections. If the sections, niacroscupic or micro- 

 scopic, are immersed in dilute sulphuric acid, after the application 

 of Lugol's solution, the,.amyloid area will assume a blue color, 

 the normal tissue a brown color. The analine dvcs usuallv stain 

 amyloid substances some shade of red. 



. The source of amylin is not delinitely known. It may he 

 derived from the blood or from tissue cells. The formation of 

 amylin may depend upon variations in the percentage of some 

 chemic substance in the blood or tissue juices. 



Amyloid formation is not common in the domestic animals. 

 Occasionally a dog is observed that is aff'ected with amyloid ac- 

 cumulations in the prostate gland. ( )ne case has been observed 

 in a hog in ^vhich tlie liver was affected, and, excepting this, the 

 carcass showed e\'idence of no other lesions. 



Etiology. — The cause of amyloid change is not known, al- 

 though it has been assumed 1)y some pathologists to be associ- 

 ated with chronic suppurative conditions, as, tuberculosis, and 

 other chronic debilitating diseases, as carcinomatosis. The 

 tissues from several animals affected with chronic suppurative 

 processes, as fistulous withers, poll e\'il, (piittor, tuberculosis, 

 glanders, caseous-iympliadcnitis, as well as tissue from animals 

 affected with tumors have been examined, l)Ut am^doid changes 

 have not been found. Increased or diminished quantity of some 

 of the salts of the blood may be found to be an etiologic factor 

 in amyloid changes. 



Appearance. — Macroscopic. — Affected tissues or organs are 

 larger, paler, and firmer than normal. The amyloid areas are 

 homogeneous and translucent in a]ipearance. The entire organ 

 or tissue appears hi'mogeneous when the amylaceous material 

 is diffuse. 



Microscopic. — Amyloid substance is deposited in the frame- 

 work beneath the endothelial cells lining the bloixl vessels. It 

 appears as an annular homogeneous mass encircling tlie vessel. 

 The amyloid substance may accumulate to such an extent that 

 the vessel is obstructed. After tlie capillaries have been gnrged 

 beyond their resistance they rupture, thus allowing the amyloid 

 substance to permeate the interstitial spaces where it appears 

 microscopically as irregular homogeneous masses. 



Tissue Affected. — The blood-vascular subendothelial con- 

 nective tissue is the principal location of amyloid formation, 

 although it mav occur in lymph vessels and even the perimysium 



