260 REMARKS ON THE STRUCTURE OF FIBRE. 



blood- disc, having the natural, flattened, concave aspect, with the mar- 

 gins of course thicker than the centre ; and it will be observed, that the 

 diameter of this disc is greater than that of any of the other more or 

 less annular ones. It is very clear, that the change of size and appear- 

 ance in the latter, is entirely owing to an alteration in the shape of the 

 blood- discs, which have assumed the form of a cup, or rather saucer, the 

 prominent edges of which, by their greater refractive power, owing to their 

 greater perpendicular depth, necessarily appear as a bright ring around 

 a darker area. That this is really the case, is proved also by the side- 

 view of the same or similarly altered blood-discs, which are represented 

 by the three crescentic figures (without letters), between the horns of 

 which the faint shadow of the distant edge of the cup could be dis- 

 tinguished by careful adjustment of the light. Now the resemblance of 

 these rings and crescents, with those figured by Dr. Barry, is sufficiently 

 obvious, to render it needless to insist upon the conclusion, that in 

 all probability the appearances are dependant in each on the same cause, 

 viz., a contraction into a cup-like form of the naturally flattened bicon- 

 cave blood-disc ; the apparent diameter of which is necessarily lessened 

 in proportion to the contraction.* 



But, if it should really be the case, that the supposed rings formed 

 by the blood-discs are in fact nothing more than the turned up edges of 

 those discs which have assumed a cup-like form : this circumstance 

 alone, would involve an important part of Dr. Barry's views with re- 

 gard to the primitive formation of muscular fibre. In a former paper 

 in the Philosophical Transactions, 1840, Part II., p. 605, he describes 

 the formation of muscular fibre, as observed by him to take place from 

 blood-corpuscles, mixed with mucus expressed from the Fallopian tube 

 of a rabbit (an extraordinary situation, at all events, for the generation 

 of muscle) ; and in his recent paper in the Philosophical Transactions, 

 1842, Part I., p. 98, and fig. 48, he represents, what he conceives to be 

 the mode of formation of muscular fibre from discs, which, " like their 

 progenitors the corpuscles of the blood, become rings, which rings pass 

 into coils, and the coils unite, thus forming spirals." If, however, it is 

 the case, as we are strongly inclined to believe, that these so-called 

 rings are themselves non-existent, but the creatures of misinterpreted 



centre, thus producing there triangular, oval, or irregular depressions. The cup- 

 shaped variety is rather frequent in corpuscles which have been mixed a little while 

 with saline solutions ; and it is not uncommon in man, particularly among the par- 

 ticles of purulent or other morbid fluids." 



* It is hardly necessary to remark, that all blood discs, even in the natural state, 

 can easily be made to appear, erroneously, as rings, or with a dark nucleus, by vary- 

 ing the adjustment of the eclairage and the quantity of light. 



