262 INFECTIOUS ENTKRO-HEPATITIS 



probable that the phigging of blood vessels in the liver by 

 parasites carried from the Cfecum is the cause of the necrosis, 

 since such plugs or thrombi are not uncommon in sections of 

 the diseased spots. 



With the appearance of the microparasites reactive 

 changes begin at once which complicate the process. We 

 have at the outset an active multiplication of the micropara- 

 sites which takes the place of the original liver tissue and a 

 process of coagulation necrosis going on at the same time. 

 Soon multinucleated (or giant) cells appear which not only 

 take in the microparasites but which are also engaged in 

 removing dead tissue. At least their collection in groups 

 around and within the necrotic areas leads to this assumption. 

 Xot infrequenth' the}" are grouped around what appears to be 

 a plugged vessel or else they occupy the lumen of the vessel 

 itself. 



In still older cases the diseased areas are found more or 

 less filled with small round cells which niaj' have passed into 

 the dead regions from the blood vessels. In all cases the latter 

 are more or less enlarged and they seem to encroach upon the 

 liver tissue, thus filling in part the void produced by the cell 

 death and giving the surface of the liver a brownish, mottled 

 appearance wherever the disease spots are. The processes of 

 advancing disease and necrosis or death of tissue on the one 

 hand and of repair on the other seem to go on side by side, 

 now one now the other predominating. 



The results of the investigations thus far made indicate 

 that the disease may follow several courses, viz.: 



( I ) After a certain period of disease regenerative processes 

 begin which tend toward a permanent recovery. 



(2) The disease may proceed so rapidly from the very 

 start that the affected turkeys die early in life. 



(3) The disease may come to a standstill but the amount 

 of dead tissue in the caeca and liver may be so great as to 

 favor the entrance of bacteria which are directly responsible 

 for the death of the bird late in the summer or fall. 



The description of the lesions of a turkey dead of this 

 disease is appended. It is quoted from Smith's report. 



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