^VATAXABE: (^X THE SO-C'ALLED BLACK HEAD OF TUKKEY. 75 



nnd which have now been destroyed. In additi<m. they occur in bile-ducts and in 

 the interlobular vessels whieii latter represent probably tlie branches of the jxirtal 

 veins. 



The parrisitic cells uiider wnsideratiou are found free in the vessels as well as 

 in the ducts, but those in the hepatic meshes are surrounded by fibrous capsules 

 which are, as it seems, extended by stages. Observations of sections through the 

 li\cr in several stages of the disease, show that the fibrous CKirpu.-cles extend them- 

 selves to the peripheral parts of the liver. The fibrous structure in this case can 

 by no means b? distinguislied from the above-stated scale-like and plate-like struc- 

 tures, containing no parasites. We are justified, therefore, in concluding that the 

 fibrous structure is pathogenoiLS in origin, being caused by the parasites, and that 

 the soale-like and plate-like structures above mentioned represent nothing else than 

 ailvanced states of the same pathological changes of tissue, although there is detected 

 no trace of parasites. In short, when the disease is advanced, the parasites disappear 

 in the plates previnusly infected, migrating into other parts where the nourishment 

 is not yet exhau-sted. 



I have nothing at present to tell with certainty about the mode, in which 

 this fibrous change of the hepatic tissue is brought about ; it is, however, highly 

 probable that this change is due to the abnormal increase of the connective tissue, 

 which forms the support of the hepatic glands, by slrimulatious of the parasitic 

 life. The host animal dies simply because the liver loses its functional |X»wer to 

 a certain degree, \\hen the pathological change in question is extended to a certain 

 extent. 



Xext we come to explain, how the parasites enter tlie substance tif the liver. 

 I have mentioned in the foregoing lines that the parasites are found m b<;>th the 

 bile-ducts and portal branches of vessels. The former institute, as I believe, tlieir 

 way escaping, while the latter represent their entrance. There is little room in 

 doubting that the parasitic cells do not travel by means of their own activity, but 

 are, to a great extent, transported in a passive way by the medium in which they 

 are found, and this nudium is represented by tlie hejiatic juice poured out from, and 

 the portal blood hasting into, the liver. It is, therefore, convincing that the 

 parasites enter the liver througli the jxirtal blood, and escape through the bile-<lucts. 



From the fiicts alx)ve pointed out, it follows that the ccecum is tlie first to be 

 attacked by the parasites, and then they come, on the way of the portal stream ot 

 blood, into the liver. The parasites in the ccecal w;dl< represent, I venture to s;iy. 



