STRIPED MUSCLE OF WASP 25 
Figure 9 (A and B) gives Schaefer’s diagrams?’ designed to 
explain muscle contraction, based upon his interpretation of 
certain wing-muscle sarcostyles of the wasp. These diagrams 
persist in some of the leading text-books of anatomy and physi- 
ology. They are only applicable to a mechanical explanation 
of contraction; and even as such misinterpret the microscopic 
Fig. 8 Photograph (by ultraviolet light) of a contracted sarcostyle from 
fly’s wing muscle teased out fresh in a mixture of equal parts of white of egg 
and a 2 per cent sodium-chlorid solution, magnified 1300 diameters (according 
to Meigs). The diameter of this contracted sarcostyle is approximately three 
times that of the relaxed sarcostyle, and the length of the contracted sarco- 
meres is approximately one-fourth that of the relaxed sarcomeres. The dark 
(contraction) band at b appears double, at a single. Meigs interprets the double 
appearance of the bands (at 6) as an optical effect due to the oblique position of 
the fiber. The writer inclines to interpret the double bands in terms of their 
double origin and an incomplete fusion of paired constituents. 
data. Diagram A is supposed to represent two sarcomeres of a 
sarcostyle in condition of relaxation. The dark disc (‘sarcous 
element’) is conceived to be double, containing medially a bisect- 
ing median (H) disc, and is described as ‘poriferous.’ The 
‘pores’ are said to be only open toward the light disc (‘hyaline 
substance’). During contraction the alleged more fluid, ‘hyaline,’ 
substance of the light disc is assumed to flow into the ‘pores’ of 
