54 H. E. JORDAN 
esis disregards almost all the facts. that are known concerning 
muscle.” On the contrary, it may be claimed that the hypo- 
thesis included all the facts that are not artifacts! Meigs states 
that the latter hypothesis “leaves unexplained the division of 
the muscle substance into minute sarcostyles, for it is impossible 
to see why larger bodies of ‘contractile substance’ should not 
perform their function as well as smaller ones.’”’ To this the 
reply may justly be made that a division of a fiber into fibrils 
each surrounded by semi-fluid extrafibrillar sarcoplasm provides 
a very much more efficient, perhaps indispensable, method of 
providing nutritive materials to a metabolically so active tissue. 
Meigs claims that the non-imbibition hypothesis also “‘leaves 
unexplained the division of the sarcostyles into sarcomeres, and 
the presence of the Z- and M-membranes, and contradicts the 
well-known fact that the Z-membrane is more or less inex- 
tensible.”’ But the presence of the Z- and M-membranes, whose 
presence imposes upon the sarcostyles a division into sarco- 
meres, can be readily and reasonably explained as paths along 
which travel the materials (assimilative and disassimilative) of 
metabolism. Their intimate attachment to the sarcostyles and 
the sarcolemma speaks strongly in favor of this interpretation. 
Meigs continues: “It leaves unexplained the differences in ap- 
pearance between the relaxed and contracted sarcostyles, and is 
forced to assume that the appearance of bulgings in the con- 
tracted sarcostyles is a delusion, and that the appearance of the 
heavy lines between the bulged areas is the result of the pro- 
duction of a large amount of some new substance within the 
sarcostyles.” However, the hypothesis which Meigs criticises 
does not asume that the appearance of bulgings (beads) in 
contracted sarcostyles is a delusion. It claims that they are 
artifacts. The illustration of a contracted fiber published by 
Meigs (fig. 8) does not actually show the bulgings which he 
attempts to impose upon it in his efforts to support MecDougall’s 
imbibition theory. The ‘heavy lines’ spoken of as between the 
‘bulged areas’ of his figure are the contraction bands formed by 
the accumulation of the darker substance of the Q-dise of the 
relaxed condition, not the result of the production of ‘some new 
