THE MIGRATING OR VAGRANT CELLS OF THE CORNEA. 379 



preserved in the lymph sacs of living Frogs, absorbed by their edges 

 into their substance, from the fluid surrounding them, numerous 

 amo3boid cells as immigrants.* 



A few years subsequently it was stated that the pus corpuscles 

 found in keratitis in the living animal, like those met with in the 

 inflammation of other organs, were to be regarded as chiefly composed 

 of immigrant white blood corpuscles which had wandered into the 

 corneal tissue. f 



It soon appeared that direct observations of a similar nature had 

 been made long before by Waller,! though they had been forgotten. 

 These observations referred essentially to the permeability of the 

 vascular walls for blood corpuscles, a process that has been demon- 

 strated by direct observation of the passage of red and white 

 blood corpuscles! | through the vascular walls. 



It thus appeared that the origin of the numerous pus corpuscles 

 met with in the cornea in purulent infiltration was to be sought in the 

 blood, and not in the corpuscles of the cornea, since the latter in the 

 infiltrated parts of the cornea are still present in a wholly unaltered 

 condition (Cohnheim). The purulent infiltration, it was concluded, 

 must always begin at the border of the cornea at that part, namely, 

 to which, as we shall hereafter see, vessels are distributed, and 

 where granular pigments, as anilin blue and cinnabar introduced 

 into other vascular regions, reappear in the pus corpuscles of the 

 cornea. IF 



At the same time, in opposition to all this, it has been shown that in 

 the excised and ulcerated corneae of Mammals and Frogs preserved 

 in one of v. Recklinghausen's propagating cells, an accumulation of 

 actively moving cells occurs around the irritated spot. Here we are 

 compelled to regard the cells as the descendants of the corneal cor- 

 puscles that have disappeared.** As regards the cloudiness that 

 proceeds from the border of a cornea made to undergo ulceratiou 

 in the living animal (His, Cohnheim), the mobile cells must indeed be 



* v. Recklinghausen, loc. tit., p. 183. 



t Cohnheim, Ueber Entziiiulu n<i mid Eiterung, (On inflammation and 

 suffocation,) Virchow's Arehiv, Band xl., p. 1. 



I Philosophical Magazine, Vol. xxix., pp. 271 and 398, 1846. 



Strieker, Sitzungsberichte der Wiener Akademie, Band lii., p. 379. 



|| Cohnheim, loc. cit., p. 38, et seq. 



1" Cohnheim, loc. cit. 



** F. A. Hoffmann, Ueber Eiterbildung in der Cornea, (On the formation 

 of pus in the cornea,) Virchow's Arehiv, Band xlii., p. 204. 



