COMPAiaSON BETWEEIT MUCUS, EPITHELIUM, AND PUS. 41 



Observations and experiments made known since the publi- 

 cation of the first edition of this work compel me to modify 

 the view I then expressed, that the formation of pus was not 

 due to wandering leucocytes ; for Cohnheim, Von Reckling- 

 hausen, Strieker, Sanderson, and others have demonstrated mora 

 or less clearly that pus corpuscles, at the commencement of every 

 acute inflammation, may be derived from the blood — i.e., that 

 they may be emigrant white corpuscles which have escaped 

 through the walls of the capillaries. But even Cohnheim 

 sees that there is nothing in the facts which contradicts the 

 previously accepted belief, supported as it is by an over- 

 whelming mass of evidence, that the later generations are the 

 offspring of the inflamed tissues by proliferation of their cell 

 elements. 



The experiments which most strongly demonstrate that the 

 white corpuscles have the power of locating themselves in 

 inflamed tissues, in virtue of their own inherent power of moven 

 ment, are as follows. Strieker irritated one eye of a frog by 

 cauterizing the cornea through, then excised the cornea of the 

 opposite eye, and inserted it beneath the membrana nictitans of 

 the irritated eye, and finally united the edge of that membrane 

 with the opposite margin of the cutis by ligatures. After 

 twenty-four hours the transplanted cornea was removed and 

 examined, and found to exhibit inflammatory changes, which, 

 although on the whole less advanced than those found in an 

 unexcised cornea at the same period after imtation, were equallj^ 

 characteristic. 



These results scarcely admit of misrepresentation ; they.are^ 

 however, rendered much more decisive and satisfactory by vary-, 

 ing the conditions of the experiments in such a way as to show' 

 that the changes observed are not due to the penetration of 

 leucocytes from the liquid in which the cornea is immersed, 

 and secondly, that they are not a mere result of its transplanta- 

 tion into an unnatural position. The first of these objects is 

 readily attained by dividing the cornea immediately after 

 excision, plunging one-half in water so as to kill it instantly,-* 

 and then placing the dead and the living portion together 

 underneath the membrana nictitans of the opposite eye. It is 

 then found that whereas the same inflammatory changes as be-; 

 fore go on in the living half, the other half remains inactive. 



