90 DR. MARTIN BARRY ON FIBRE. 



of the filament it produces. In the other Vertebrata, the discs contained within the 

 blood-corpuscle are too numerous-}- for such a ring ; therefore their arrangement 

 forms a coil. At the outer part of this coil, the filament (already stated to be flat) 

 is often on its edge (figs. 10, 11, 12), from which arises a greater thickness of the 

 corpuscle, and the appearance it has of being cut off abruptly at this part ; while in 

 the centre, there is generally the unappropriated portion of a nucleus (figs. 8, 10) : 

 whence the central eminence, around which there appears a depression in those cor- 

 puscles that, from the above cause, have the edge thickened. 



3. The nucleus of the blood-corpuscle in some instances resembles a ball of twine, 

 being actually composed, at its outer part, of a coiled filament (fig. 10 /3, y). 



4. Such of the Invertebrata as I have examined (figs. 14, 15), likewise present the 

 blood-corpuscle passing into a coil. 



5. Acetic acid dissolves the part most advanced, leaving the newest part behind. 

 This accounts for the figures accompanying my Part II. on the Corpuscles of the 

 Blood %, representing corpuscles of Birds, Amphibia, and Fishes, from which the 

 filament in question, or its elements, had been removed by this reagent. 



6. The filament thus formed within the blood-corpuscle, has a structure which is 

 very remarkable (see the figures just referred to). It is not only flat, but deeply 

 grooved on both surfaces ; being thereby thinner in the middle than at the edges. 

 The edges are rounded : and when seen on its edge, the filament at first sight seems 

 to consist of segments. It is important, however, to observe, that the line sepa- 

 rating the apparent segments from one another, is not directly transverse, but oblique 

 (see fig. 9 y). 



7. Of course the structure of an object so minute, cannot be seen without a very 

 high magnifying power, and a good light. And it may be here remarked, that in 

 the researches forming the subject of this paper, I have generally added dilute spirit 

 (sp. gr. about 0'940), containing about -j^oth of corrosive sublimate^. 



8. It is deserving of notice, in the first place, that portions of the coagulum of blood 

 sometimes consist of filaments having a structure identical with that of the filament 

 formed within the blood-corpuscle ; secondly, that, in the coagulum, I have noticed 

 the ring formed in the blood-corpuscle of Man (fig. 4), and the coil formed in that 

 of Birds (fig. 6) and Reptiles, unwinding themselves into the straight and often 

 parallel filaments of the coagulum, changes which may be also seen taking place 

 in blood placed under the microscope before its coagulation ; thirdly, that I have 

 noticed similar coils strewn through the field of view (figs. 7, 17) 5 when examining 

 various tissues, the coils here also appearing to be altered blood-corpuscles, and 



f Philosophical Transactions, 1841, PI. XVIII. figs. 52 y, 54 e. In all vertebrated animals the young blood- 

 corpuscle is a mere disc, with a depression in the centre. In Mammalia it continues of this form ; while in 

 the other Vertebrata it becomes a nucleated cell. J L. c., PI. XVIII. 



For the examination of certain tissues, especially muscle, I have since used chromic acid sp. gr. about 1-050. 



