226 E- A. Schäfer, 



Contraction- appearances of the alcohol- fibres. 



As for the changes in the sarcostyles which accompany con- 

 traction, these, so far as they are elucidated by the appearances of 

 muscles fixed in alcohol, are sufficiently shown in the figures of re- 

 tracted (Figs. 39, 42) and extended (Figs. 40, 41) fibres, and may 

 be briefly stated to be identical with those exhibited by the wing 

 sarcostyles. 



These changes, accompanied as they are by a shortening and 

 bulging of the sarcous elements and a diminution of the clear inter- 

 vals, must necessarily produce changes in the intervening sarcoplasm. 

 The most prominent change, so far as my observation goes, is to cause 

 the sarcoplasm to become accumulated opposite the ends of the 

 muscle-segments, corresponding to the constrictions which usually 

 appear here in the contracted fibre. This accumulation becoming added 

 to that which was previously there in the form of the transverse 

 networks, occupies an interstice which in longitudinal view, has a 

 lozenge shape (Fig. 9); and in contracted fibres stained by the ordinary 

 gold method, the lateral series of these enlargements may give the 

 appearance of a broad interrupted dark line crossing the fibre and 

 joined longitudinally to those of the next series by fine lines of inter- 

 columnar substance. This dark line is at first double, but as the con- 

 traction proceeds the two dark lines blend into one (Figs. 7, 8). While 

 this is undoubtedly the ordinary change which is seen in the sar- 

 coplasm of the retracted (contracted) as compared with the extended 

 fibre, it is sometimes the case that in portions of fibres which have 

 been stained with gold in the ordinary way or which have simply 

 been acted upon by weak acid, there are also enlargements of the 

 sarcoplasm opposite the middle of the muscle segments, which take 

 the form of bulgings upon the longitudinal lines of the apparent re- 

 ticulum. It is not necessary, however, to assume with van Gebuchten 

 and Ramon y Cajal that these enlargements are due to contraction 

 of the sarcoplasm (the reticulum of those authors) for their presence 

 may be quite simply explained either by supposing that there existed, 

 prior to the contraction of these particular fibres, local accumulations 



