DR. MARTIN BARRY ON THE CORPUSCLES OP THE BLOOD. 225 



The Elements of the Pigmentum nigrum, and those of the Ciliary Processes, compared 



tixith Corpuscles of the Blood. 



1 1 7. 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-f-. 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 J'" to 5'", I find the blood-corpuscles to contain, situated on 

 the nucleus, certain red globules (fig. 75. a.), appearing to transform themselves into 

 discs (/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 



t L. c, Tab. II. figs. 8 and 9. 



