Miscellaneous. 151 



In Fishes, Batrachia, and even Reptiles, this arrangement occurs 

 even round the aorta. In them the lymphatics are applied to the 

 arterial vessels, of which they embrace one-half, three-quarters, or 

 even the whole. The true capillaries, and even some small arteries, 

 which diverge from the principal blood-vessels, traverse these lym- 

 phatics transversely, and are thus completely immersed in the lymph 

 for a short portion of their course ; sometimes even a branch of the 

 lymphatic accompanies them. This arrangement merits notice, 

 because something analogous to it is met with about the capillaries 

 of the encephalon and spiral marrow of the Mammalia*. 



From the whole of these facts, it seems to result that the chief 

 use of the lymphatics is to charge themselves with the excess of 

 that portion of the blood- plasma which arrives in the capillaries, and 

 issues from them at each systole of the ventricles. In fact we 

 know that the quantity of lymph flowing is much greater when 

 there is a considerable afflux of blood to an organ than when the 

 latter is in a state of repose. 



Moreover I have ascertained, by the examination of living Rays 

 in M. Goste's laboratory at Concarneau, that the great lymphatic 

 vessels contain only a few drops of lymph when they are opened 

 several minutes after the removal of the fish from the water. This fact 

 coincides with the paleness of the intestine and the state of com- 

 parative vacuity of the vessels. This lymph is more abundant when 

 the animal is opened immediately on its removal from the water, and 

 when at the same time the intestine still contains food in course of 

 digestion ; then also the blood-vessels contain more blood. 



There is reason to think that under certain conditions of the life 

 of these fishes, which live at a great depth, these large ducts are 

 full, or nearly so, when certain modifications of the circulation, of 

 the kind just indicated, occur. 



In the cavity of the lymphatic, between the concave inner surface 

 of its free wall and the convex outer surface of the capillary to 

 which the other portion of its wall is applied, the following pheno- 

 mena may be detected by the microscope : — In the living animal a 

 hyaline lymph holding leucocytes in suspeusion is seen circulating. 

 The movement of the leucocytes is oscillatory, but with a slow pro- 

 gression in a direction opposite to that followed by the blood in the 

 contiguous artery. The leucocytes of the blood are carried along by 

 the blood-corpuscles, but more slowly than the latter, and they may 

 be seen momentarily arrested against the inner concave surface of the 

 capillary and separated from the lymph by its wall. The leucocytes 

 of the lymph are the only elements perceptible in that liquid ; and 

 no red globules are found in it. These leucocytes (in the mesentery 

 of the lizards which were the subjects of my observations) are about 

 one-third smaller than those of the blood ; they float in the liquid 

 for the most part, and only a few are applied to the inner surface of 

 the lymphatic. They are also rather less granulated than those of 

 the blood. Their outline is darker, like that of the leucocytes 



* C. Robin, Journal do la Physiologic, 1859, pj). 537 & 719. 



