ALIMENTARY CANAL, ETC., OF AMIURUS CATUS. 411 



Eberth 1 also describes them as ending in the same manner, but also 

 finds that they are lined by a doubly contoured membrane very 

 delicate and 'browning in silver nitrate injections. This membrane 

 is no where isolable or independent of the cells in contact with it, 

 and is absent altogether in fishes. Haidenhain and Peszke, 2 by fill- 

 ing the gall capillaries with sodium sulphindigodate and macerating 

 the liver tissue in a solution of potassic bichromate and sodium 

 chloride obtained the capillaries filled with the blue compound com- 

 pletely isolated as minute pieces of tubules, formed of a doubly con- 

 toured membrane otherwise apparently structureless. 



My observations agree in the main with those of Hering and 

 Eberth : in the case of the latter author as far as the structure of 

 the capillaries in fishes is concerned. 



In uninjected livers it is almost impossible to find the gall capillary. 

 On the other hand, when injected artificially or by the natural 

 method, it is of considerable breadth. Injection of silver nitrate 

 will but fix and harden the adjacent portions of the liver cells, and 

 thus is formed, apparently only, a capillary membrane. Peszke's 

 method will not show the presence of an independent capillary in 

 fishes. From these facts I would conclude that the capillary is an 

 intercellular passage, which in hardened sections is absent, but which 

 during life exists by reason of the power of the cells to select and 

 deposit in that particular position the necessary products of its secre- 

 tion. If the cell is in active secretion the passage has a greater 

 diameter. If secreted products be absent, or if they be dissolved 

 out, as is the case in hardening reagents, the passage disappears. 

 The presence or absence of it therefore is much like the presence or 

 absence of a lumen in the gastric glands in some vertebrates. 



The gall-bladder is not folded to any extent on its inner surface 

 when in the fresh condition. In hardened portions when the muscular 

 coat has shrunken, the mucous coat is thrown into minute folds. 

 These two coats are not sharply distinguishable. The outer bundles 

 of muscular tissue are longitudinally arranged, but in quantity are 

 very few. They frequently take an oblique direction, especially 

 about the mouth of the bladder and in the cystic duct. The inner 

 circularly arranged coat of muscular fibres is by far the thickest. 

 Into it the fibrous tissue of the mucous coat enters and frequently 



1 Virchow's Archiv, Bd. 39, and Arch, fur Mikr. Anat., Bd. III. 



2 Hermann's Handbuch der Physiologic, Bd. V. 

 29 



