344 THE LYMPHATIC SYSTEM, BY F. v. RECKLINGHAUSEN. 



inflammation in the exposed mesentery of the frog, where he 

 saw the colourless corpuscles, which,, as usual whenever the 

 blood current is retarded, accumulate in the lateral quiescent 

 layer, and traverse the vascular walls, especially those of the 

 veins, in order to migrate in the well-known mode ; and thus the 

 observation formerly made by Waller* in 1846, but again for- 

 gotten, except in England, under the predominant influence of 

 Virchow's teaching, has reassumed its proper position. Hering 

 has moreover observed in the mesentery, when spread out 

 under the microscope, that the escaped colourless blood cor- 

 puscles enter into the lymphatic vessels ensheathing the blood- 

 vessels, in order to be transported to other parts as lymph 

 corpuscles. On these grounds we shall certainly be inclined to 

 regard this doctrine as well founded ; nevertheless, in spite of 

 considerable attention to this question, I have been unable to 

 arrive at any very positive conclusion, and cannot avoid 

 making a few observations. In the first place it is certainly 

 not easy to follow a particular corpuscle through its whole 

 course from the blood current through the venous wall into 

 the surrounding tissue, or to exclude the suspicion that the 

 escaped cells proceed, not from the vascular wall, but from the 

 adjoining connective tissue layers; secondly, the migration 

 does not occur immediately after the exposure of the mesentery, 

 but only after the lapse of some hours, when the most serious 

 retardations and disturbances of the circulation have occurred. 

 It is true I have been able to observe the migration of colour- 

 less blood corpuscles under much more favourable circumstances, 

 and without remarkable alterations of the blood current, in 

 the tail of narcotised tadpoles, not only in the capillaries, but in 

 the small veins and arteries, and on these grounds I should not 

 object to accept the doctrine that the migrating cells of the 

 connective tissue proceed from the blood current, were it not that, 

 (1) in consequence of the narcotisation, a certain retardation of 

 the circulation was present ; (2) that it was embryonal tissue 

 that was under examination ; and (3) that other observations 

 are adducible, admonishing us that, with such movable elements, 

 and structures so disposed to wander, we must exercise extreme 



* S. Kosinski, Wiener Med. Wochenschrift, 1868, Nos. 56 and 57. 



