Royal Society. 383 



digestion of food, forms, from the blood supplied to it, abundance of 

 sugar, which thus appears to be its proper secretion ; and it is not 

 proved that the hepatic cells in a healthy state contain biliary matter, 

 though they often do in various morbid conditions. Extracts of the 

 hepatic parenchyma tested for bile by Pettenkoffer's method, give 

 only very imperfect and doubtful traces of the presence of biliary 

 matter, and on the other hand the sugar formed by the parenchyma, 

 which is found so abundantly in the blood of the hepatic vein, is 

 absent from the bile. The case of fatty liver, as occurring either 

 pathologically or normally, seems also to require an explanation 

 consonant with the view to which the above facts point, for other- 

 wise it seems impossible to understand how perfectly formed dark- 

 green bile could be contained in the efferent channels of a gland 

 whose tissue is a mass of oil. 



The structural condition of the ultimate biliary ducts is compared 

 to that of the epithelium of the thyroidal cavities, and the nucleated 

 granular tissue surrounding the lacteal in a villus ; and it is shown 

 to be probable that the terminal portions of the ducts, — so far as they 

 possess the peculiar characteristic structure, exert an active elabo- 

 rating energy, by means of which bile is formed or generated out of 

 oily, albuminous or saccharine material which surrounds, — may be 

 said to bathe them. 



Feb. 5. — The following papers were read : — 



1. "Discovery that the veins of the Bat's wing, which are fur- 

 nished with valves, are endowed with rythmical contractility, and 

 that the onward flow of blood is accelerated at each contraction." 

 By T. Wharton Jones, F.R.S., Fullerian Professor of Physiology 

 in the Royal Institution of Great Britain, &c. 



The author finds that the veins of the bat's wing contract and 

 dilate rythmically, and that they are provided with valves ; some of 

 which completely oppose regurgitation of blood, others only par- 

 tially. The act of contraction of the vein is manifested by pro- 

 gressive constriction of its calibre and increasing thickness of its 

 wall ; the relaxation of the vessel, by a return to the former width 

 of calibre and thickness of wall. The rythmical contractions and 

 dilatations of the veins are continually going on, and that, on an 

 average, at the rate of ten contractions in the minute. The con- 

 tractions centrad and distad of a valve appear to be simultaneous, as 

 also the dilatations. 



During contraction, the flow of blood in the vein is accelerated, 

 and on the cessation of the contraction, the flow is checked, with a 

 tendency to regurgitation, which brings the valves into play. But 

 this check to the onward flow of the blood is usually only momen- 

 tary ; already, even while the vein is in the act of again becoming di- 

 lated, the onward flow recommences and goes on, though with com- 

 parative slowness, until the vein contracts again. It is the heart's 

 action which maintains the onward flow of blood during the dilata- 

 tion of the vein, whilst it is the contraction of the vein, coming in 

 aid of the heart's action, which causes the acceleration. 



The valves are composed sometimes of but a single flap, some- 



