190 E - A - Schäfer, 



meaning will be clearer when we have considered the structure of the 

 wing-muscles. 



Without at present further burdening - the subject by discussing 

 points of detail which are, after all. not material, let us come back 

 to the main question, which, in its ultimate form, is simply this, „Is 

 a muscular fibre composed of longitudinal elements or not?" Before 

 proceeding to answer this question it is necessary to define the terms 

 which I shall have to use, although in doing so I shall be compelled, 

 in a measure, to state the ultimate conclusions at which I have arrived. 

 But unless a clear definition of terms precedes any description of this 

 tissue, it is very possible that the meaning of any statement may be 

 entirely misconstrued. For example, while Rollett uses the term fibril 

 in the sense in which it was originally and is usually employed, van 

 Gebuchten and Ramon y Cajal denote by the same term the sub- 

 stance which lies between the fibrils of Rollett, or at least between 

 groups of his fibrils. 



General conclusions arrived at. Definition of terms. 



The main substance of a muscular fibre, the part which exhibits 

 alternating dim and bright cross-striae, and winch remains unstained 

 when treated by the ordinary acid -gold method, is separable into 

 longitudinal elements. These have often been termed fibrils, but in 

 some muscles they themselves appear fibrillateci: they are therefore 

 better termed muscle-column* (Kölliker) or sarcostyles. 1 ) The muscle- 

 columns are separated from one another, and at the same time united 

 together to form the fibre, by an inter-columnar material which, with 

 Rollett, I shall term sarcopiasm. Certain enlargements of tliis sar- 

 coplasm form transverse networks which appear as such in cross- 

 sections of the fibres, but in longitudinal view look like rows of dots. 



The rest of the sarcopiasm gives in longitudinal view the appear- 

 ance of longitudinal striae. A fine membrane crosses each muscle- 

 column at regular intervals corresponding with the middle of the 



') Guoi, muscle; gtûXoç, a column. 



