THE STRUCTURE OF THE ELEMENTARY TISSUES. 



87 



following: That the muscle-fibre consists of longitudinal fibrillse 

 grouped together into muscle columns, which are seen in the transverse 

 section as Cohnheinr's fields, and that the intercolumnar material is 

 semi-fluid sarcoplasm. A muscle column consists of segments alter- 

 nately thin and thick, while in the centre of the thin portion is a dark 

 enlargement forming a dot, these dots in Cohnheim's arrangement cor- 

 respond to Krause's membrane. 



In fresh muscle, at low focus, according to this view, the muscle- 

 columns appear dark and the sarcoplasma appears light, the former are 

 in a line with the granules. At high focus, the reverse is the case, but 

 the dark sarcoplasma is now seen in line with two rows of granules 

 (fig. 89). 



Also, that in gold-stained preparations, the dark row of granules are 

 thicknesses of the sarcoplasma between the thin segments of the muscle 



Fig. 89. Diagram of the appearances in fresh muscle-fibre. A. At low focus (B) the muscle 

 columns appear dark and in a line with the granules, sarcoplasm light. At high focus (A) the sarco- 

 plasm is dark, muscle columns light, and two rows of granules appear in a line with the sarcoplasm 

 and alternating with the muscle columns. (Marshall, after Rollett.) 



columns, whereas the two rows of granules do not correspond with 

 these, but alternate with them, belonging as they do to the muscle 

 columns, and not to the sarcoplasm. 



Schiifer has thrown considerable light upon the controversy by hav- 

 ing actually observed that when a small portion of the living wing- 

 muscle of insects is teased up with needles in a small drop of white of 

 egg, the sarcostyles may easily be separated from their surrounding 

 sarcoplasm, and may be actually seen to contract, whereas the sarcoplasm 

 shows no such property. According to this observer such a sarcostyle 

 may be examined thus isolated, both living and after treatment with 

 various reagents, and it shows alternate bright and light stripes, the 

 latter being bisected by a line which corresponds wtih Krause's mem- 

 brane. Krause's membrane divides the sarcostyle into sarcomeres, which 

 contain in the middle the strongly refractive disc-like sarcous element, 

 and above and below it hyaline material, which is bounded by Krause's 

 membrane. The sarcous substance is penetrated by canals, which ex- 

 tend upward and downward from the hyaline substance to the middle. 



