OZ H. E. JORDAN 
establish the histologic basis upon which an adequate theory 
ean be built. The evidence discussed above makes it clear 
that contraction is not a simple imbibition phenomenon. The 
fundamental physicochemical or electrical processes upon which 
contraction directly depends are restricted to the intrasarcostylic 
sarcoplasm. How the alterations in the striations are related 
to these processes and how both are fundamentally related to 
contraction can at present only be surmised. Prenant, Bouin, 
and Maillard'® conceive of contraction as an electrocapillary 
process. They describe the process as follows: 
When the electrical potential of opposite surfaces of contact between 
the particles of the muscle fiber becomes modified in some way, as by 
a nervous stimulus or by energy liberated by a chemical reaction, the 
form of these surfaces tends to become modified, . . . . resulting 
in a contraction of the fiber. The striated fiber, where occur triple 
contacts between the dark disc, the clear dise and the sarcoplasm, is 
much more sensitive than the smooth fiber, and its division into aggre- 
gations of very small particles, in consequence of which it becomes 
very active from the point of view of capillary attraction, gives to the 
whole considerable energy. Since there is a reciprocity between the 
surface deformations and electrical variation, a simple shock (mechan- 
ical stimulus) produces a variation in potential, which, by propagation 
also determines contraction. Contraction appears to beaccompanied 
by aslow usage of the albuminoid substances of muscle, with the forma- 
tion of creatin bases, but the principal chemical change consists in the 
appearance of a large quantity of lactic acid, which either partially or 
totally becomes converted into carbonic anhydride and water. This 
lactic acid forms to the detriment of muscular glycogen and especially 
to the glucose continually supplied by the blood; the sugar of the blood 
is then the primary source of the energy, but during the work of muscle 
contraction, the reserve hydrocarbons of the muscle tissue play a 
secondary role (p. 414). 
The outstanding morphologic mark of contraction is the con- 
traction band. This structure is composed essentially of fused 
opposite halves of successive dark discs and a bisecting telo- 
phragma. The intermediate phases when the Q-disc is bisected 
by a widening H-dise has until now been most difficult to explain. 
The usual interpretation of these latter phases, namely, as the 
result of a stretching of the sarcostyle, has led to much confusion. 
This interpretation has apparently adequate observational sup- 
port, for sarcostyles with divided Q-discs, that is sarcostyles at 
