DR. MARTIN BARRY ON THE CORPUSCLES OF THE BLOOD. 223 



maintains that it is a nucleus, — the object usually termed the nucleus, being really 

 the nucleolus. From my own observations, it appears that, paradoxical as it may 

 seem, both these views admit of being established. The fact is, that at an early period 

 the corpuscle of the blood is a mere disc, having a cavity or depression representing 

 the " nucleolus." At this period the corpuscle may be called a nucleus ; though it 

 does not seem desirable to use this term, before the formation of the cell. Subse- 

 quently, the outer portion of the corpuscle or disc becomes transformed into minuter 

 discs, which coalesce to form a membrane ; and the inner portion is now the nucleus, 

 the entire corpuscle being a cell. 



111. At a of fig. 144. is a corpuscle resembling a young corpuscle of the blood, in 

 which the central part was red, and the outer part pale. At a, fig. 95, is a blood- 

 corpuscle, the discs in the altered nucleus of which, generally speaking, had a deeper 

 red, the nearer they were to the centre of the nucleus. These may serve as examples, 

 showing that there is a continual re-appearance of red colouring matter, and that it 

 comes into view around the orifice in the nucleus. 



Epithelium-tables, cells, and cylinders compared with Corpuscles of the Blood. 



112. On examining the tail in a great number of Tadpoles, — the larva of the large 

 Toad found in Jersey, — these Tadpoles measuring from 4'" to 6'" (Paris lines) in 

 length, I found the central part of the epithelium-tables to present an appearance so 

 varied, that it would have been vain to expect that, by figuring those of any one part, 

 an idea could be given of their general appearance. Nor can I hope to have yet done 

 so ; but it seemed desirable to sketch a few of the states noticed, without regarding 

 the relations of the tables to one another, and without confining myself, in the de- 

 lineation, to the same individual. 



113. Before referring more particularly to these, I will just express my surprise at 

 its having been possible for any one to examine the tail of a single minute Tadpole, 

 without recognizing in its epithelium, corpuscles having the same appearance as cor- 

 puscles of the blood. And I see no way of reconciling the acuteness of observers 

 with the absence of this recognition, except by supposing the Tadpoles examined to 

 have attained a far greater size than those examined by myself — measuring chiefly 

 from 4'" to 5'". In those of the lengths now mentioned, ] find it impossible to discern 

 an essential difference in appearance between the objects entering into the formation 

 of the edge of the tail, and blood-corpuscles circulating in this larva (par. 196.). The 

 comparison is very easy, if made after the corpuscles are at rest within their vessels. 

 It frequently happens too, that the placing of a piece of glass or mica upon the tail, 

 lacerates the edge, and separates epithelium-tables from it (fig. 86. a, /3.) ; when it 

 is seen that these tables, in their form, size, colour, and internal state, have the same 

 appearance as the blood- corpuscles which were circulating just before, in the same 

 field of view. 



114. The nucleus in some of the epithelium-tables fig. 86, bore a curious resem- 



