463 



The author has succeeded in demonstrating the communication 

 between the ducts and cell-containing network in several mamma- 

 lian animals, as well as in the human subject, by injecting the ducts 

 in the manner described. Of these, the seal, hedgehog, rabbit and 

 Guinea-pig have afforded the best specimens. 



In Birds, the continuity in injected specimens has been traced in 

 the common fowl and in the turkey. The quantity of epithelium in 

 the ducts of birds forms a great obstacle to the passage of the injec- 

 tion, and from their extreme tenuity, the capillaries do not bear the 

 preliminary injection of much water. 



Reptiles. The author has seen the continuity between the ducts 

 and cell-containing network, in an uninjected preparation of the 

 newt's liver, and in an injected liver of the adder. 



Fishes. In consequence of the very fatty nature of the liver of 

 fishes, it was found to be very difficult to harden it sufficiently to 

 cut thin sections. The frequent presence of entozoa and their ova, 

 renders it difficult to inject the ducts. The author succeeded in 

 injecting the ducts and part of the cell -containing network in the 

 sturgeon and in the Lophius, and in one instance, those of the very 

 fatty liver of the cod. The continuity was also traced in an unin- 

 jected liver of the common flounder. The injection often passes a 

 certain distance into the finer ducts of fishes, but cannot be forced 

 into the cell-containing network. In this way the appearance of 

 blind terminations to the ducts is produced, as the continuity of 

 the tube cannot be traced beyond the point at which the injection 

 stops. 



The continuity of the finest ducts with the cell-containing net- 

 work has been demonstrated in all classes of Vertebrata, both in in- 

 jected and also in uninjected specimens. In all the livers of verte- 

 brate animals which have been examined, the duct becomes much 

 narrowed at the point where it joins the network in which the cells 

 lie. The arrangement of the small ducts varies somewhat in dif- 

 ferent animals. Sometimes a network of minute ducts is formed, 

 which is continuous with that in which the cells lie. In other in- 

 stances the communications between these terminal ducts are very 

 few in number, or are altogether absent. Upon the latter point the 

 author does not express himself positively, as he is sure that in the 

 most perfect injection which he has been able to make, the whole of 



