192 E. A. Schäfer, 



work enlargements of the sarcoplasm occur. In the wing-sarcostyles 

 a faint longitudinal striation can be detected in it. 



We may now return to the consideration of the question, 



Are there grounds for believing that longitudinal elements (muscle- 

 columns) pre-exist in the muscle-fibre? 



I do not see how this question can be answered otherwise than 

 in the affirmative. For in the first place it is admitted that after 

 death of the tissue, and after fixation by many reagents, the substance 

 of the fibres even of the ordinary muscles can be split up into longi- 

 tudinal elements. Why this should be so if there is no pre-existing 

 structure of the kind, I, for one, entirely fail to comprehend. In any 

 case the onus probandi rests upon those who affirm the absence of 

 such pre-existence and the difficulty of proof is evidenced by the 

 different explanations which have been offered for the phenomenon. 

 Thus while most of those who hold the reticulum-enchylema theory of 

 muscle -structure conceive that the fibrils of alcohol -hardened muscle 

 are produced by an artificial splitting along planes which include the 

 longitudinal lines of the so-called reticulum, van Gebuchten maintains 

 that the splitting is between those lines, and that the alcohol fibrils 

 are the longitudinal fibrils of the reticulum plus a greater or less 

 amount of the inter-reticular substance which has become precipitated 

 on those fibrils! 



In criticising these explanations, it may be remarked that the first 

 is, at least, not inconsistent with the actual fact, viz: that the splitting 

 into muscle-columns passes through the longitudinal lines of the ap- 

 parent network. This can be seen if an alcohol preparation which 

 exhibits the muscle -columns, but in which the sarcoplasm (reticulum) 

 is invisible or obscure except as clear lines between the columns, be 

 taken and dilute formic acid cautiously added. The sarcoplasm comes 

 out in the form of dark lines between the muscle-columns: these dark 

 lines are the longitudinal lines of the so-called reticulum. They are 

 not, therefore, enclosed within the muscle -columns as van Gebuchten 

 affirms. But although the first view is so far consonant with the 



