208 Dr Martin Barry on the 



seen, and it is important to observe : — 1. That in the early 

 stages of its formation the cytoblast of Schleiden has no nu- 

 cleolus, but acquires a nucleolus before its formation is com- 

 plete. 2. That when the cytoblast has formed a cell, the 

 nucleus of this cell is what had been the nucleolus of the cy- 

 toblast ; and, 3. That now another nucleolus comes into view 

 in the situation which had been occupied by its predecessor. 

 4. That this process continuing the same, the nucleus of one 

 stage is the nucleolus of an earlier stage ; there being a con- 

 tinual succession of nucleoli in the centre. 5. That it is a 

 process which begins before the complete formation of even 

 Schleiden' s cytoblast ; in fact begins with the existence of 

 the minute pellucid globule, which thus becomes transformed 

 into that cytoblast. 6. That this process is the very opposite 

 of that described by Valentin in his statement of the united 

 views of Schleiden, Schwann, Miiller, Henle, and himself, as 

 forming the elements of tissues. 



Figs. 1 to 15 represent the process in no more than the 

 primary or main centre of each cytoblast and cell ; they would 

 have been complicated by any attempt to exhibit it in the 

 secondary centres; where, however, abundant evidence is 

 afforded that the process is the same, for the secondary cells 

 fill with other broods in like concentric order, and leave no 

 doubt whatever that every segment of the nodular or star- 

 like hyaline in fig. 8, after having become a globule, passes 

 through in succession the conditions represented in figs. 2, 3, 

 and 4, before it becomes a cell. (And hence it seems to be, 

 that the process is obscured by immeasurably minute and 

 highly refracting globules). 



Wishing to confine the foregoing remarks as much as pos- 

 sible to the mode and order of formation of the cytoblast, the 

 cell, the nucleus, and the nucleolus, — I have hitherto said 

 nothing in this paper of an orifice often seen by me to connect 

 the nucleolus with the exterior of the cytoblast and cell ; and 

 adding much to the refraction of light which takes place at 

 that point. This orifice, which I first saw in the germinal 

 spot in 1840, will be found represented in many figures, and 



