DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 209 



79. Now this mode of origin of cells of comparatively large size, may perhaps assist 

 us in the consideration — how are the minuter ones produced ? I formerly stated-f- 

 that it was not easy to point out where the disc terminates, and the cell begins ; and 

 that I did not recollect to have observed any of the discoid objects in the transition 

 state in question, in which there was not an appearance in the most superficial part 

 .denoting decomposition. I added, that so uniformly had this been met with that I 

 was ready to suppose the formation of the cell-membrane to be connected with such 

 decomposition, or perhaps dependent on it. From later observations, I am more 

 and more disposed to think that this really is the case ; and that exceedingly minute 

 discs, into which the outer portion of a larger disc has been resolved, coalesce to 

 form the membrane of the cell. Thus in fig. 54. the outer portion of discs such as 

 those at a, seemed at ^ to have resolved itself into minuter discs, which at y were 

 more advanced, and at S had coalesced to form the membrane of the corpuscle or 

 blood-cell. 



80. It will be seen from what I have in this memoir, and elsewhere, stated, that 

 the disc ("nucleus" of authors) is the most primitive object we are acquainted with. 

 It will also be perceived that the cavity or depression ("nucleolus") in the disc, is 

 the situation of the future orifice, communicating with the exterior of the cell. The 

 nucleus of the cell seems to be reproduced by the fissiparous mode. 



81. The objects into which the nucleus of the mammiferous blood-corpuscle sepa- 

 rates (fig. 23.), are no doubt the source from whence proceeds the substance for the 

 origin and thickening of the chorion, and the formation of the muscular fibril J. 



82. The process by which the nucleus of the cell finally divides into several parts, 

 seems to consist in the originally single and pellucid cavity or depression in the nu- 

 cleus, gradually becommg finely granular (see the explanation of fig. 43.) ; and by 

 degrees separating into several cavities. An idea of this change may perhaps be ob- 

 tained from the condition of the nucleus in the blood-corpuscle ^, fig. 45. 



83. The nuclei which several observers have found lying among the fibres of vari- 

 ous tissues, have been considered by them as the " remains of cells." This may have 

 been the case ; but so far from thinking, with those observers, that the nuclei in 

 question were " destined to be absorbed," I am disposed to consider that they were 

 the sources from which there would have arisen new cells. See, for instance, deline- 

 ations by Schwann of nuclei lying among fibres from a feather (/. c. Tab. II. fig. 13.). 

 (And I may here take the opportunity of remarking, that I apprehend the fibres in 



t Third Series. Additional observations, par. 439. Note. 



X See my Third Series on the Embryo, /. c, and also the figure accompanying a Supplementary Note to that 

 Third Series, in the present volume, p. 193 ; as well as my first paper on the Coqjuscles of the Blood, /. c. 



