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a deep red colour, and burst into view. Almost at the same 
moment a point in the wall of the corpuscle gave way, and 
a very finely granular matter issued, which was stained red 
by the magenta, whilst, at the same time, a red “ macula” 
formed internally at the point whence this had escaped. A 
second macula, accompanied with the escape of matter which 
took up the red colour, formed very shortly afterwards at 
another point of the corpuscle (fig. 23d). I thus saw that the 
molecular matter, stained red in the plasma, was due to the 
escape of something from the corpuscles themselves, identical 
with the macule. ‘The action of tannin (fig. 24) appeared 
to me to be very closely similar to that of magenta, excepting 
that the matter which escapes and forms a coloured mole- 
cular mass in the plasma when magenta is used, in the case 
of tannin is arrested and “set” as it escapes, thus forming 
the pullulation. That it is not always set, and that much of 
it escapes, may be seen from Roberts’ figures, as also I ob- 
served in both human and frog’s corpuscles. 
I merely point to the sketches of human corpuscles treated 
with magenta and with tannin in order to confirm Roberts’ 
description of them (fig. 22 a, 6). The phenomenon is much 
better studied on account of size in the corpuscles of the frog. 
The magenta ‘ macula’ in the human corpuscle almost invari- 
ably appeared to stand out a little from the surface, to be a 
very little raised, as it were, which is not the case in the frog. 
The reason I believe to be the greater delicacy of the pellicle 
or membrane of the corpuscle in Mammalia than in Ovipara. 
There can, I think, be little doubt as to the identity of the 
magenta macula and the tannin pullulation. The questions 
which occur are: Is the Robertsian macula a physiological 
or a cadaveric differentiation ? and what is the nature of this 
substance which thus takes up the magenta dye and is 
coagulated by tannin? As to the first question, there appears 
to be no ground for supposing that this differentiated ‘macula’ 
exists during the life of the corpuscles, since, as is obvious 
by their form, and the steps of the process as described above, 
the whole corpuscle is very much altered before the macula 
or pullulation makes its appearance. Moreover, they occur 
with great irregularity in the frog’s corpuscle as to number 
and position, and, as observed by Dr. Roberts in the oval 
corpuscle of the camel, the usually single macula appears to 
have no definite position. It seems to me, then, likely that 
this macula is due to the separation or segregration of a con- 
stituent of the blood-corpuscles, which occurs as a cadaveric 
change under the influence of some reagents. The material, 
whatever it is, collects at the most yielding point or points 
