18 PROCEEDINGS OF THE ACADEMY OF [Biolog. 



The interlobular and lobular hepatic ducts do not arise from the glandular 

 plexus, but they can always be traced back to larger ducts. 



In front of the vena cava, where it passes the substance of the liver, I 

 have found a very dense plexus of the peculiar vessels with follicular appen- 

 dages already described, and of others without them. A portion of it, about 

 one inch long and half an inch wide, consisted of several layers of these ves- 

 sels, distinctly enclosed between two layers of the capsule. A network of ar- 

 teries, similar to that found in other parts of the capsule, was seen in the lay- 

 ers of the latter. The plexus itself I observed both in the injected and fresh 

 specimen, communicating or arising from large vessels, which, by a close ex- 

 amination, proved to be the lymphatics of that region, by the valves they pos- 

 sessed. Almost around the whole vena cava at this place, anastomoses of the 

 above described vessels can be seen. 



The description of the microscopic lymphatics of the liver I shall give in my 

 next essay on this subject. 



The interlobular branches of the portal vein and hepatic artery are derived from 

 a plexus which is formed by some of their branches in their capsule. 



Some of the branches of the hepatic artery penetrate to the surface of the 

 liver ; they are tolerably large and anastomose freely with each other in the 

 capsule. From the anastomoses thus formed, .smaller branches proceed, which 

 again in their turn give origin to still smaller ones. The latter vessels, when 

 viewed under a low magnifying power, have the appearance of a broken net- 

 work of large capillaries with large meshes, and as such they have been re- 

 garded and described by other anatomists. However, if examined more closely 

 in well injected specimens, we find that they form no network of their own, but 

 terminate in the capillaries of the lobule. 



The portal vein also sends small branches to the surface, which, however, 

 do not anastomose with each other. They accompany the larger branches of 

 the hepatic artery, (mostly the second set in size, above mentioued, ) to termi- 

 nate likewise in the capillary- network of the lobule. Thus, there exists no other 

 communication between the branches of the hepatic artery and those of the por- 

 tal vein on the surface of the liver, except through the medium of the capillaries 

 of the lobule; and the blood of the artery, instead of returning, to the portal 

 vein, as has been asserted, is with that of the latter discharged into the ca r 

 pillar ies of the lobule, by which route it arrives directly in the branches of the 

 hepatic veins. 



The analogy of the blood vessel on the surface of the liver to those in the 

 interior of the organ I shall prove in my next essay. 



II. Therapeutics. 



Dr. Leidy read a paper, entitled " On the seat of the vesicating principle of the 

 Lytta vinata.'* 



From the experiments detailed in this paper, it appears that the vesicating 

 principle of the Lytta vittata belong to the blood, the peculiar fatty substance of 

 certain accessory glands of the generative apparatus, and to the eggs. 



III. Toxicology. 



Dr. Morris related several cases of poisoning from the sting of the common 

 bee. In one case, a man died in a very short period of time after the injury 

 was received. In this instance the sting was received in the cervical region 

 In a second case, an adult was seized with convulsions, which lasted for a con- 

 siderable time. There was during these convulsions complete opisthotonos. 

 He stated that some thirty or more cases, similar to these, have been reported. 



*See the American Journal of the Medical Sciences, for January, 1860. 



[Sept. 



