320 Dr Martin Barry on 



of the " cytoblast " and cells of coagulating blood.* That 

 paper will be found to contain drawings w r hich afford ex- 

 amples — 1. Of the blood-disc or "cytoblast" giving origin 

 to a ring or coil of fibre for the formation, in some instances, 

 of the primary membrane of the blood-cell, into which pri- 

 mary membrane it is actually seen passing ; 2. Of the nucleus 

 of the blood-cell giving off fibre to form secondary membranes 

 or other deposits ; and 3. Of division of the cell. The follow- 

 ing appears to be the process effecting these three changes. 



The " cytoblast," so called, is at first an exceedingly mi- 

 nute particle of the substance which, from its appearance, I 

 have been accustomed to term hyaline. It enlarges, and at 

 the outer part becomes finely granular. (There occurs no 

 deposition of granules around it, as many have imagined.) 

 It is soon seen to be flat and elliptical. At first it is never 

 round, a fact of which my drawings in the Philosophical 

 Transactions for 1841 afford countless examples, though I 

 believe I have never mentioned it before. "f It becomes round, 

 and is now in essentially the same state as a circulating 

 mammiferous blood-disc (which also in all the Mammalia, as 

 I long since shewed, is elliptical at the first). Its finely- 

 granular outer part corresponds to that which is red in these 

 blood-discs. When destined to form a cell it becomes in- 

 vested by a membrane. In order to the formation of this 

 membrane, there occur the following changes : — The pellucid 

 centre, called the nucleolus, gives off globules. These glo- 

 bules appropriate and assimilate the finely granular substance 

 of the outer part of the " cytoblast " into which they were 

 cast, and furnish the material out of which there is formed a 

 ring or coil of fibre. This ring or coil of fibre passes into 



^ In all vertebrated animals the young blood-corpuscle is a mere disc (" cyto- 

 blast''). In Mammalia it circulates in this form, while in the other Vertebrata 

 it becomes and circulates as a nucleated cell. (This was stated in my paper 

 "On Fibre," loc. cit., 1842.) — The evolution of red colouring matter forms one of 

 the most remarkable changes in coagulation of the blood, and of this coagulation 

 the formation of fibre constitutes the leading part. — The arrangement of them- 

 selves by the mammiferous blood-discs in rolls like rolls of coin, seems to de- 

 note the tendency, not merely to form fibres, but to arrange them. 



t Others have described it merely as " sometimes oval, and sometimes round." 



