218 DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 



have to offer : and I can scarcely expect the reader to admit the conclusions drawn, 

 until he is in possession of the unequivocal evidence, to be derived in no other way 

 than by a close examination of the Plates, in connection with the explanation just 

 referred to. 



I may here mention, that it is not my object in this memoir, to trace the tissues 

 investigated into a perfectly formed state ; but simply to present such of their earliest 

 stages, as show them to be derived from objects having the same appearance as cor- 

 puscles of the blood. In so doing, I shall have to mention a variety of facts, which, 

 though met with incidentally, and recorded without remark, may not be considered 

 destitute of physiological interest. 



88. It is important that any one disposed to repeat the following observations, 

 should, before entering upon them, carefully notice the colour, — the transparent yellow 

 colour, — of the corpuscles of the blood, viewed singly, with a high magnifying power 

 (as, for example, the corpuscles in blood obtained by a puncture of the finger) ; so 

 that when the same colour is met with elsewhere, he may recognize it. The yellow 

 of the magnified corpuscle as thus singly viewed, is obviously that which gives to the 

 mass of blood — seen with the naked eye, and by reflected light — its well-known red. 

 The reader will bear this in mind, when colour is spoken of in the following memoir. 



89. Some of the observations I am about to communicate, will be found at variance 

 with those of other investigators in general anatomy, not excepting even the most 

 recent. I have not room, within the limits of a paper, to introduce the opinions of 

 the authors referred to. 



90. On former occasions, I have mentioned a certain minute structure, under the 

 denomination disc. As the same term will be constantly employed in this memoir, 

 it is better, once for all, to define it, as a flat, elliptical or circular body ; usually 

 having a concavity in the middle of the flat surface (fig. 141 h,l, s.). Frequently, 

 however, these minute bodies lose their elliptical or circular form, and assume, as if 

 by pressure, a polyhedral shape ; and, in certain states, the concavity becomes an 

 orifice. There are also conditions in which a minute projection is presented at this 

 part. Numerous examples of discs are to be found in almost every figure which ac- 

 companies the paper. 



91. The disc seems in many instances to correspond to the " cytoblast" of Schlei- 

 DEN ; though his description of the " cytoblast" differs in some material points from 

 the definition I have given of the disc-f- : and our experience of the destination of these 

 objects is no less diff'erent. In the proper place it will be shown that the disc has 

 been described by some as a peculiar object, found in two or three kinds of globules. 



92. By division into discs, an expression frequently made use of in this paper, I do 

 not mean simple separation. For, from the analogy which seems to exist between 

 the mode of propagation of the blood-corpuscle, and that of the cells which are the 

 immediate successors of the germinal vesicle in the ovum, there cannot be a doubt 



t See Third Series on Embryology, Philosophical Transactions, 1840, Part IL pars. 385, 425. 



