44 H. E. JORDAN 
b. Sarcosomes 
Sarcosomes occur both in the leg and the wing muscle of the 
wasp. In the mantis I could detect sarcosomes only in the wing 
muscle. In the leg muscle of the wasp (fig. 18), as in the wing 
muscle of the mantis, they occur as two distinct groups; a group 
of smaller spherical elements (J-granules) on either side of and 
close to the telophragma, and a group of larger oval elements 
(Q-granules) along the midline of the dark dise. Both in the 
leg muscle of the wasp and the wing muscle of the mantis these 
eranules are dissolved by alcohol, but are preserved in tissue 
fixed with strong Flemming’s fluid or a 10 per cent formalin 
solution. This microchemical reaction suggests an essentially 
lipoid nature. The most plausible interpretation of these 
eranules that all the available data support is that they are 
formed in close association with the telophragma, the latter 
furnishing the pathway by which their constituent elements are 
carried from the intersarcostylic tissue spaces, and that as they 
grow in size they become crowded toward the middle of the 
sarcomere (perhaps aided in this movement by muscle con- 
traction), and here modified into oval structures through the 
mutual pressure of adjacent sarcostyles. Their function may be 
assumed to be nutritive. The above interpretation necessitates 
the further inference that the larger sarcosomes are continually 
used up through the functioning of the muscle fiber, and new 
ones continually formed in the vicinity of the telophragma. 
The J-sarcosomes le at the levels of the accessory dise (com- 
pare figs. 14 and 18). This spatial juxtaposition has led certain 
investigators (Retzius, ’902') to interpret the accessory disc as 
composed of J-sarcosomes; therefore, a structure composed of 
intersarcostylic elements. Again, the overlapping of the con- 
traction bands in contracted fibers with the two series of J- 
granules has given a basis for the conclusion (Retzius,?! Holm- 
gren,® and Heidenhain®) that the contraction band (disc) is 
produced by the aggregation of J-granules. The error of such 
explanation of the accessory dise and the contraction band is 
proved by the presence of both of these structures in fibers in 
