THE LYMPHATICS AND ENTERIC EPITHELIUM 

 OF AMIA CAIvVA. 



GRANT SHERMAN HOPKINS. 



The comparatively small number of investigations upon 

 the lymphatic system of Fishes and Fish-like Vertebrates ap- 

 pears the more remarkable when we consider the capacious- 

 ness and the undoubted importance of this great vasiform 



system. 



A possible explanation for this lack of attention on the 

 part of zoologists may be found in the difficulties attendant 

 on any investigation of these vessels owing to the trans- 

 parency and delicacy of their walls and the liability of con- 

 fusing them with the veins. To whom is due the credit of 

 having first discovered the lymphatic system in fishes, we 

 will not attempt to decide. Hewson and Monro both claimed 

 the honor, but it is pretty well established that the lacteals of 

 a fish were observed more than a century before by Bartholin^ 

 (2) though his description was alloyed with the old error that 

 they terminated in the liver. It is doubtless true, as remarked 

 by Abernethy that "all our knowledge of the absorbing 

 vessels has been obtained by fragments, and that our future 

 acquisitions must be made in the same manner. ' ' It must be 

 allowed, however, that the lymphatic system of the lower 

 vertebrates, especially the osseous fishes, was more completely 

 exhibited by Hewson (8) than by any of his predecessors or 

 contemporaries. 



Hewson's three papers on the lymphatic system in birds, 

 amphibia and fishes, appeared in the Philosophical Transac» 

 tion for 1768-69. In the paper on fishes he gives a 

 description of the lymphatic vessels in the Haddock together 

 with some of the more striking pecularities of this system in 



* See References. 



