STRUCTURE OF THE COCCIDIA. 207 



Psorosperms from the liver, and although, on the other hand, others 

 (Vulpian, Koloff) have claimed the liver cells themselves as the germs 

 of the Coccidia, there can be no doubt of the above fact. Every well 

 prepared cross section furnishes convincing proof 1 (Fig. 109). 



The wall of the Coccidium-nodulQS consists of a thick firm mass of 

 connective tissue with frequent nuclei and fibres, usually arranged 

 concentrically. Besides numerous blood-vessels, one can not unfre- 

 quently recognise, especially towards the periphery, smaller and larger 

 groups of liver-cells and of bile-ducts, which, although enlarged in 

 varying degrees, may be only slightly changed and often still contain 

 a regular columnar epithelium. 



We might perhaps explain these appearances by supposing that 

 the connective tissue wall increases continually in thickness at the 

 expense of the liver substance, while the adjacent acini proliferate and 

 are crowded together in an ever widening circle. 2 



This proliferation of the connective tissue takes place not only 

 outside the nodules, but extends also along the duct into the remoter 

 recesses. Where the acini are usually found crowded in close layers, 

 one finds in the diseased liver numerous bands of connective tissue of 

 varying thickness, which are embedded between the lobules. These 

 enclose a number of bile capillaries, which are often separated from 

 one another only by thin septa, but here and there include little areas 

 of the liver substance between them. These are essentially the same 

 changes as are observed in cases of severe hepatic cirrhosis, except 

 that in the latter the degeneration is restricted to this stage of develop- 

 ment, while here it goes further, inasmuch as at certain points where 

 the Coccidia have nested the bile-ducts widen and thus occasion 

 the formation of new nodules. Thus also it happens that the cysts 

 are often associated together, and can sometimes be extracted from 

 the liver as a root-like branched system of varicose cords. 



At first sight these Coccidiicm-nodul.es may be seen to be utterly 

 different from the bile-ducts, even from those which were enclosed in 

 the bands of connective tissue. They have not only a wide saccular 



1 I can only explain the opposite opinions by the supposition that the investigators 

 have neglected to make sections of sufficient fineness. 



2 Thus we understand the repeatedly expressed opinion that it is the acini which 

 represent the proper source of the disease. Thus Koloff (Archiv f. pathol. Anat., Bd. 

 xliii., p. 522) states that the nodules arise by exuberant growth of the connective tissue 

 in and between the liver lobules, and that they change into Coccidia internally. Lang 

 (ibid., Bd. xliv., p. 202) refers the commencement of the disease to the liver lobules, and 

 describes it as a proliferation of cells, which takes place around the interlobular vessel, 

 and gives rise at once to the destruction of the glandular tissue and the formation of a 

 fibrillar connective tissue, which afterwards undergoes a retrograde metamorphosis from 

 the centre outwards, and thus produces the Coccidia partly from the alteration of the 

 cells grouped together in nests resembling cords. 



