200 E - A - Schäfer, 



therefore, under the influence of the reagents a shorter time. Finally 

 the deepest parts of the tissue are not reached at all by the chloride 

 of gold. At the junction of those parts of the muscle which have not 

 been touched by the gold and those which have been reached and 

 have undergone the ordinary staining, there will be a certain number 

 of fibres to which the gold has only just penetrated, a part only of 

 a fibre exhibiting gold staining. Whether the preliminary acid reached 

 these fibres before the gold chloride penetrated to them, it is impos- 

 sible to say. It is precisely in these fibres which have evidently been 

 only just reached by the gold solution, that the appearance shown in 

 Figs. 17 and 18 is sometimes obtained. This appearance is very 

 striking. The double rows of dots which, in the longitudinal view 

 (Fig. 17) represent the sections of the transverse networks, are darkly 

 stained by the gold so as to appear almost black. All else, including 

 the longitudinal lines of the sarcoplasm, is absolutely clear and co- 

 lourless. In the surface view of the transverse networks the fibres 

 of these networks, so far as the gold has penetrated and become 

 deposited in them, are also violet black (Fig. 18). Under the sarco- 

 lemma the dark lines end abruptly, the sarcoplasm which is described 

 by Rollett as lying immediately within the sarcolemma, as well as 

 that which lies between the muscle-columns elsewhere, shows no trace 

 of staining. 



I do not know how otherwise to interpret these appearances 

 than by the supposition that the transverse networks are not merely 

 accumulations of the ordinary inter-columnar sarcoplasm, but that they 

 contain in addition a substance having chemical peculiarities different 

 from the rest of that sarcoplasm. What this différence may be due 

 to, it is not at once easy to say, but the extreme affinity which they 

 exhibit for the gold salt may perhaps point to their representing the 

 remains of the granular protoplasm of the original formative muscle 

 cell. The fact that they are continuous with the protoplasm around 

 the line of central nuclei is in favour of this view, which was indeed 

 the view taken by G. Retzius. It is possible that in those muscular 

 fibres in which the nuclei are situated under the sarcolemma, the 

 transverse networks may be continuous with a layer of hyposaröo- 



