B. M. NELSON ON STRIPED MUSCLE FIBRE OF PIG. 3 



former paper, it is stated tliat I had seen two white stripes, one 

 on either side of a known dark stripe ; but now we have 

 a dark stripe in the middle of a known white one. The 

 explanation of this is that the previously known stripe was 

 an optical ghost, which became white or black according to 

 focas, due to the customary small cone of illumination. There- 

 fore, if it is called black, my discovery consists of two white 

 stripes; and if it is called white, then mine is a black stripe. 

 What I claim is that, instead of one stripe, be it black or white, 

 there are three, in the order of white, black, white. 



The most important point in the photograph which has been 

 faithfully represented by Mr. Karop is in the last dark space 

 but one from the bottom. Here the new dark stripe jDrotrudes 

 beyond the edge of the fibrilla. This affords a conclusive proof 

 that this stripe is an entity. In my anxiety to secure this 

 detail another is sacrificed. A drawing which combines the 

 points gathered from several photographs would probably 

 explain the subject more clearly, but as these points have been 

 so much controverted, it is perhaps better to keep to the 

 one negative. In some of the photographs a longitudinal white 

 stripe is seen, which apparently divides the fibrilla into two 

 portions. It is this longitudinal white stripe which gives that 

 beaded appearance which has been often noticed. It will be 

 observed that it is the white portions which are the weaker, 

 the fracture always occurring there. On the left-hand side 

 there are no less than three fractures taking place at the trans- 

 verse bright white stripes and one at the longitudinal. It 

 would seem that what we have called an ultimate fibrilla of 

 TTWWo i^ich in diameter is almost ready to break into two 

 fibrin ae, each being •28^(nr ii^ch in diameter. 



The longitudinal white stripe is not so strongly marked 

 where it crosses the Krause membrane, and it is very likely 

 owing to that fact that the fibrilla has not split up. The 

 above structures, in comparison to those of diatoms, are coarse, 

 and of their being entities there cannot be the slightest doubt. 

 With regard to the physiological theory of the action of muscle 

 I^ have no knowledge, but it is evident that theory must 

 square with the structure of muscle as we find it, and not, 

 as is often the case, the structure made to square with an a 

 priori theory. The magnification is 1,750 diameters. 



