526 Dr. G. Thin on the Anatomy of 



One or more round holes are, however, seen on the pieces of broken muscle- 

 cylinder, the more conspicuous because the nuclei are absent ; they are 

 about the size o the blood-corpuscle of the frog. By changing the focus, 

 it is seen that each hole is only on one side of the fibre. The sharp 

 clearness of their outline shows they are not artefacts, but spaces in which 

 the sarcolemma is wanting (figure 23, Plate XI.). A further action of 

 potash is seen when a muscular fibre is found channelled with one or more 

 canals parallel to the long axis of the fibre. The canals thus seen are 

 uniform in breadth ; they are formed by rows of vacuoles, which corre- 

 spond in shape and size to the nuclei of cells. (I had observed in study- 

 ing the cornea that the first stage of the destruction of the flat cells, in the 

 potash solution, is a vacuole taking the place of the nucleus.) By changing 

 the focus, it is seen that these channels are in the substance of the fibre. 

 Smaller channels and single vacuoles are seen in different planes. 



A more extended degree of the action of potash on a fibre is when the 

 central canal has no longer sharp outlines and is seen to contain granular 

 debris. 



Treatment of muscular fibre by haematoxylin gives, as regards nuclei, 

 results confirmatory of those got by potash, in so far as a still greater 

 number of nuclei are seen internal to the sarcolemma than is indicated 

 even by that method. To obtain the best results from haematoxylin, the 

 fibres should be isolated before being dyed. The excess of colour being 

 removed by acetic acid, the nuclei become distinct ; they are seen to be 

 arranged in long rows, those of one row being in the same plane. Isolated 

 nuclei are seen in different planes. An idea of their number is best 

 formed from the appearance presented by the broken end of a fibre when 

 it is turned upwards, giving a view equivalent to a transverse section. 

 The whole thickness of the fibre is then seen to contain nuclei, in the ar- 

 rangement of which something of a concentric disposition can generally 

 be observed. The nuclei are large and oval, and contain one or two 

 distinct nucleoli. If the substance of the fibre has been teased, it is seen 

 that the fibrillae are arranged in bundles which have an equal thickness, 

 and isolated nuclei are seen adhering to their surface. 



The inferences that are irresistible from these appearances prepare the 

 way to readily understanding the more decided effects of an appropriate 

 treatment by chloride of gold. The conditions of a successful examina- 

 tion of a muscular fibre by gold include the detachment of the perimysium 

 from the fibre without injuring the latter, the obtaining good transverse 

 views in the preparation, and the requisite degree of colouring. As it is im- 

 possible to ensure beforehand a combination of these favourable condi- 

 tions, it is evident that, with equal care, success is not uniform. The 

 results which I now give were obtained by teasing the muscles of the 

 thigh of the frog in aqueous humour before staining with gold. 



In the most perfect preparations thus obtained, the structure of a mus- 

 cular fibre is seen to be almost identical with that of a fasciculus of 



