GEOWTH OF THE COCCIDIA. 209 



us also with the most convincing evidence that the nodules, in spite 

 of their distention and the very different nature of their contents, 

 are identical with the former bile-ducts. One can see the original 

 columnar epithelium 1 of the latter slowly pass into the above-men- 

 tioned cell-masses, and in such a manner that the individual cells, 

 influenced by the pressure and growth of the included Coccidium- 

 germs, alter very considerably inform and size. Not only the super- 

 ficial, but also the deeper epithelial cells share in this change, and 

 the more so since an active cell-multiplication is very often pro- 



FIG. 109. The epithelium of a Psorosperm-nodule, filled 

 with parasites. 



gressing simultaneously. As a rule, however, one finds in the larger 

 Psorosperm-nodules considerable spaces with a but slightly altered 

 columnar epithelium (Fig. 109). In other places all likeness to the 

 earlier stage is lost. Here and there the cellular layer is wholly 

 destroyed, so that the connective tissue projects without covering, 

 though the cells are usually replaced by a more or less thick, shining, 

 structureless layer of considerable consistency, and probably of a 

 colloid nature, as Lang has already mentioned. 



What I have observed as to the growth of the germs, and the 

 consequent changes of the cells, agrees in the main with the descrip- 

 tions given by previous observers of the intestinal epithelium cells 

 infected with Psorosperms. I must, however, note that the examina- 

 tion of the intestinal epithelium, as I know from experience, presents 

 less difficulty, and shows the true state of the case on the whole 

 more readily. 



The most difficult point, of course, is the demonstration of the 

 newly arrived parasites. I can say nothing definite about them. 

 The smallest germs I was able to distinguish with certainty were 

 slightly granular roundish masses of protoplasm of about 0*009 to 

 O'Ol mm., containing a comparatively large and clear nucleus-like 



1 According to Lang, these columnar cells have been formed anew in the proliferation 

 of the connective tissue, and have then further grouped themselves in tubular nests. 







