Purser — On Inflammation and Suppuration, 161 
feeling in favour of Cohnheim, and with almost a wish to find him 
right. I have, ho vvevor, been quite unable to confirm his results, and I 
find it every day more and more difficult to understand how he could 
ever have observed the appearances which he records. My own 
observations have been made chiefly on the corne£e of frogs. I have 
examined also a great number of frogs' tongues. In these the connective 
tissue corpuscles are pale and difficult to see, and the field soon becomes 
covered with emigrated white blood cells, which increases the difficulty 
of observation. The tongue is, however, an admirable object in which 
to see the passage through the vascular walls of the leucocytes — indeed 
it was in it that this phenomenon was first observed by Dr. "Waller. 
The best mode of examination is that recommended by Cohnheim. The 
animal is poisoned with a small dose of ciirara, and, when motionless, 
laid on his back on a large slide, on which a raised piece of glass of 
suitable size and shape, and surrounded by a margin of cork, has been 
cemented. The tongue is drawn out of the mouth and laid on the piece 
of glass, and fastened by small pins to the cork. A small piece of the 
mucous membrane is clipped off one part of the tongue with curved 
scissors. This causes hardly any bleeding, and as it is the papillary 
surface of the tongue which is now uppermost, the removal of the 
mucous membrane greatly increases the transparency of the object. 
The tongue may then be submitted to examiuation with high or low 
powers. If it shows any tendency to dry, it may be moistened with a 
weak saline solution, or with artificial serum ; but this is rarely neces- 
sary. The phenomena observed in the tongue are described by Cohn- 
heim as precisely similar to those seen in the cornea. The white cor- 
puscles pass out through the vascular walls, and the connective tissue 
cells remain quite unaltered throughout the process. Strieker has, 
however, seen the pus corpuscles, whether emigrated from the vessels 
or formed outside, multiply by division ; and he has observed an active 
movement of the connective tissue cells. I have frequently seen the 
markings described by Strieker as appearing on the leucocytes prior to 
their division. I have, however, never observed the complete separa- 
tion of one corpuscle into two. This I attribute mainly to the great 
difficulty I have found in keeping the circulation in the tongae per- 
fectly normal during the prolonged examination necessary to observe 
the inflammatory process. Our frogs are certainly less well adapted 
for physiological experiments than those used on the Continent, and 
very many of my experiments have failed, I believe, in consequence of 
the feebleness and low vitality of the animals I had to employ. 
I proceed now to detail the results I have obtained by my observa- 
tions on the inflamed corneae of frogs. In these the inflammation was 
excited either by cauterising the centre of the cornea with a fine point 
of nitrate of silver, or by passing a thread through the bulb behind the 
corneo-scleral junction. Some specimens of spontaneous ulcerative 
keratitis (a disease from which captive frogs very frequently suffer, 
particularly in the summer months) were examined, and in some in- 
stances the inflammation was induced by drawing a seton through the 
K. I. A. PROC— VOL. II., SBB. II. 
Y 
