192 Dr Barry's Observations on Fibre. 



Fig. 18. Side view of the Zoe of the Cm'cinug mcenm, a short time after it 



has escapetl from the ovum. 

 ... 19. Appearance of the Larva of the Ccdigus piscinus, sometime after it 



has escaped from the ovum. 

 ... 20. Mature ovum of the same. 

 ... 21. Ovum in an early stage. 

 ... 22. Ovum a little farther advanced. 

 ... 23. Young Caligus taken from the egg ; it is at a more advanced stage 



than the last. 

 ... 24. Extenial oviduct of Caligus, shewing the escape of the ova, and 



how they remain attached until the young are hatched. 



Additional Observations On Fibre, contained in aM^emoir lately 

 read to the Hoyal Society of London, By Martin Barry, 

 M.D., F.R.S., Lond. and Ed. 



On examining coagulating blood, the author finds that it 

 contains discs of two different kinds ; the one comparatively 

 pale ; the other, very red. It is in the latter discs that a fila- 

 ment is formed ; and it is these discs which enter into the for- 

 mation of the clot ; the former, or the pale discs, being merely 

 entangled in the clot, or else remaining in the serum. He thinks 

 that the filament escaped the notice of former observers, from 

 their having directed their attention almost exclusively to the 

 undeveloped discs which remained in the serum, and thus con- 

 ceived that the blood-discs are of subordinate importance, and 

 are not concerned in the evolution of fibrin. 



To render the filament distinctly visible, Dr Barry adds a 

 chemical reagent capable of removing a [portion of the red 

 colouring matter, without altogether dissolving the filament. 

 He employs for this purpose chiefly a solution of one part of 

 nitrate of silver in 120 parts of distilled water ; and sometimes 

 also the chromic acid. He admits that the use of these 

 reagents would, on account of their destructive tendency when 

 concentrated, be objectionable as proofs of the absence of any 

 visible structure ; but as the point to be proved is, that a cer- 

 tain specific structure does exist, he contends that the same 

 appearance would not equally result from the chemical actions 

 of reaijents so different as are those of chrome and the salts of 



