DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 
225 
The Elements of the Pigmentum nigrum , and those of the Ciliary Processes, compared 
with Corpuscles of the Blood. 
11/. The general appearance of black pigment, as seen, in a formed state, in the 
choroid coat of the eye, is well known. And that variety of this substance met with 
in the tail of the Tadpole, has been accurately represented by Professor Schwann, in 
a certain stage-j~. As to the mode of origin, however, of this substance, in either of 
the localities just mentioned, I am not aware that we possess any published informa- 
tion : a remark equally applicable to the blackish substance found in mucus from 
the air-passages. Perhaps the following observations, therefore, may be useful. 
118. In Tadpoles of 4^"' to 5"', I find the blood-corpuscles to contain, situated on 
the nucleus, certain red globules (fig. 75- «•)> appearing to transform themselves into 
discs ( 1 3 ) of the same red colour. Now in the epithelium-tables above mentioned, as 
so much resembling the blood-corpuscle, the peripheral part is composed of red 
discs. The red discs of several tables are necessarily in contact. They coalesce, and 
present the appearance delineated in fig. 89. Each line of discs in this figure, it will 
be seen, is made up of those derived from two adjacent tables. These discs, quite 
red in the figure now referred to, subsequently divide into extremely minute, blackish 
objects, which adhere together, and form partitions between the central portions of 
the tables. In a state more advanced, it is not easy to discern this partition-like 
appearance, nor to connect the very irregular forms into which the partitions are 
distorted, with their original figures of six sides. At y in the figure last mentioned, 
is a stage more advanced than that at (3 ; but the objects were still seen to be com- 
posed of discs. They also presented a trace of the partition-like appearance, and 
were still red. In fig. 91, are stages of these objects yet more advanced (but from 
another part), and apparently corresponding to those figured by Schwann from the 
tail of the Tadpole. In the latter stages they are known under the name of pig- 
ment ramifications, — of which I think the observations now detailed, may assist to 
show the mode of origin. 
119. The large object connected with the pigment ramifications (figs. 90, 91.) 
appears to be a centre for the reproduction of epithelium-tables ; for those in fig. 88. 
are corresponding objects, in which this reproduction is very obvious — the pellucid, 
germinal vesicle-like nucleus on one side of the object figs. 90 and 91, being, more 
particularly, the centre from which the reproduction proceeds. 
120. But one of the figures just referred to (fig. 91.) was taken from the pigment 
of the eye ; which seems to be produced in a manner precisely such as that just 
described, as giving origin to similar appearances in the tail. This will be obvious, 
I think, if the object on the right hand in fig. 93. (eye) be compared with fig. 89. (tail). 
And each of these presents a centre for the origin of new substance (the peripheral 
discs), like the centres just referred to. (Fig. 93. will be found fully described in the 
f L. c., Tab. II. figs. 8 and 9. 
