On Absorption. 167 



Nuclei of capillaries aud connective tissue. 



Having ascei'tained that applying magenta to the conjunc- 

 tiva produced no irritation, I hoped that its gradual absorp- 

 tion into the system might reveal to us certain particles and 

 hitherto ill-defined forms of structure, and that possibly the 

 passage of such particles (germinal matter of Beale, his- 

 togenetic molecules of Bennett), might be traced from one 

 pai't of the body to another ; but I must say that a great deal 

 of laboui' has brought me a very little way on, still I am 

 not without hope that I may yet lay something more 

 definite on this subject before the Society. 



It matters not whether these dj^es are injected into the 

 peritoneal ca^dty or beneath the skin, they almost immedi- 

 ately make their appearance in the urine. Very little incon- 

 venience attends the operations, and even after injection into 

 the pleural ca^dty life is not endangered. Thus I have 

 injected the same animal or bird eight and ten times ; if care be 

 not used, however, inflammation is produced, most probably 

 from the point of the instrument wounding some of the 

 viscera. In the two cases where death resulted, the peritoneal 

 cavity was found full of icncoloured serum and lymph, at the 

 same time that the dye had disappeared ft-om the urine 

 before death. 



We have now to determine by what route the dye passes 

 from the abdomen or fi^om beneath the skin to the kidneys ; 

 certainly not directly. Knowledge familiar to us all is against 

 such a view. To appear, therefore, in the urine, it must 

 have been brought from the heart by the arteries to the 

 kidneys. Our most direct course is to examine the contents 

 of heai't soon after injecting the dyes. For this purpose 

 I performed the following experiments : 



Expervnient 1. — A fr^og was injected beneath the skin 

 with equal parts of blue &jq and water. Four hours after I 

 exposed the heart, tvithout disturbing the pericardiiiin, and 

 saw the blood deeply dj^ed, flowing into and out of the 

 heart with each relaxation and contraction of the ventricle. 

 The blood in the femoral artery was also dyed, as were all the 

 tissues moi^e or less. 



Experiment 2. — Another fr'og was injected with yellow 

 dye. In twenty minutes, by the same proceeding as above, 

 the circulation of yellowish blood was seen. All the tissues 

 slightly tinged. 



Expervnient 3.— Magenta dye similarly used, and 

 magenta-coloured blood seen circulating. 



