268 E. A. ANDREWS 
INTERNAL ANATOMY OF THE SECOND STYLET 
Dissections and sections showed the presence of the same gen- 
eral structures as in the case of the first stylet, with the important 
difference that the special glands of the tube of the first stylet are 
absent and on the other hand the intrinsic muscles that are ab- 
sent in the first are well developed in the second stylet. The 
muscles are arranged as in the younger stages (figs. 27, 28). Be- 
sides the three muscles at the base that pass into the sternum of 
the second abdominal somite a very short distance there are long 
muscular strands within the stylet itself. 
The protopodite springs from a considerable elevation of the 
sternum and in the adult two muscles were found within this 
elevated articular region. Pulling one tended to depress the sty- 
let into its position of rest while the smaller muscle was thought 
to be probably concerned with the erection of the stylet. Pull- 
ing all the basal muscles made the stylet not only he down but also 
move toward the median line, which would enable it to fit in nicely 
with the first stylet. Some of these extrinsic muscles extend a 
distance into the protopodite itself, to be attached to the shell. 
There are also long strands arising from the shell of the protopo- 
dite and running to the exopodite and the endopodite. Those of 
the exopodite seem associated with the basal muscles, so that pull- 
ing the muscle in the sternum made slight twitching movements 
of the exopodite, simulating those seen during conjugation, which 
may thus be caused by contractions of the muscles that hold the 
entire appendage in position. Pulling the muscles that are in the 
distal part of the protopodite made both exopodite and endopo- 
dite move dorsally and also away from the median plane. 
The muscles that move the exopodite are better developed than 
those of the endopodite. Within the exopodite there is a long 
intrinsic muscle that would seem fit to bend the slender filament 
slightly. Inside the endopodite, beside the slight muscles of the 
base concerned with the movement upon the protopodite, there are 
in the adult two slight threads that represent the muscle seen in 
early stages (figs. 27,28) passing from the terminal flagellum down 
