384 
beneath the cecoid or pellicle of the corpuscle, and there, 
forced by increased contraction of the more solid parts of the 
corpuscle, bursts out through the pellicle, escaping to a large 
extent in the case of magenta, and becoming diffused, but 
becoming fixed as a pullulation when tannin is used. It seems 
probable that the separation and escape of this constituent of 
the corpuscle goes on under the influence of other reagents, 
but that being neither stained nor precipitated by them we 
do not see it. Thus, after weak ammonia has been allowed 
to act, I found that neither human nor frog’s corpuscles 
exhibit the macula with magenta. In the frog’s red corpus- 
cle so treated, the nucleus remained unstained in many cases, 
whilst the body took up the colour (fig. 23 f)—a similar result 
to that described above as to acetic acid and as to ammonia. 
Frogs’ red corpuscles acted on with chloroform tothe third stage 
did not give the magenta macula, though the nuclei stained 
well. Frogs’ red corpuscles treated with aqueous vapour till 
they assumed the rounded form did not give the macula 
with magenta. Frogs’ red corpuscles dried, as also human 
ones dried, did not, on treatment with magenta, give the 
macula, though the nuclei of the former stain most readily 
and brilliantly (fig. 23 g). 
The reason that the ammoniacal solution of carmine does 
not bring out the macula as does magenta is probably due to 
the ammonia causing solution of the substance, whatever it 
may be, which is thus segregated or squeezed out from the 
rest of the corpuscle. The absence of the macula in dried 
corpuscles is easily understood as due to a prevention of the 
contraction which causes the separation of it under certain 
reagents from the other constituents of the corpuscle. 
By further microchemical research, no doubt, the nature 
of the substance which forms the macula and pullulation 
may be more definitely ascertained. I am inclined to be- 
leve it to be a more fluid constituent of the body of the 
corpuscle. 
It is especially necessary to remark that neither magenta 
nor tannin act on one part only of the red blood-corpuscle. 
They both affect it through and through. The connection 
of the molecular matter, supposed to belong to the plasma by 
Roberts with the macule, as seen by me, is of especial sig- 
nificance as to the mode of origin of the latter, and its con- 
nection with the tannin pullulation. 
Experiments with certain gases remarkable for their combi- 
nations with the hemoglobin of the corpuscles. 
19. Effect of carbonic oxide.—CO, as is well known, forms 
a compound with hemoglobin, having a characteristic ab- 
