550 A. B. DAWSON 
Authors have quite generally agreed that the expulsion of the 
granular secretion is due to the contraction of the smooth muscles 
found about the gland sacs. Seeck (91), however, believes 
that the expulsion of secretion is caused by the underlying skeletal 
muscles. Muhse (’09) has experimented with many toads and 
has found that there is no change of tension produced in the 
skin when the glands are discharging. She concludes, therefore, 
that the expulsion of secretion cannot be due to any action of the 
trunk muscles. Evidence in support of Muhse’s contention is 
also furnished by conditions in Necturus, since, in the regions 
of the edges of the tail where granular glands are present in 
great numbers, no skeletal muscles occur, the glands lying in 
the loose connective tissue which fills the space between the 
integument on either side of the tail. Since in Necturus there 
are no smooth muscle fibers present in the dermis, other than 
those definitely arranged in the walls of the glands, we may 
conclude with a fair degree of certainty that the expulsion of the 
granular secretion is a direct result of *the contraction of the 
muscles immediately about the gland. The appearance of the 
muscles of emptied glands and the manner of their innervation 
also support this view. 
In Necturus the contraction of the muscles usually proceeds 
uniformly over the entire surface of the glands. Occasionally, 
however, deep furrows or constrictions in the gland bodies were 
noted. These are apparently due to differences in the rate of 
contraction of individual fibers. It will be recalled that the 
muscle fibers lie in a meridional direction on the gland sac and 
that the upper ends of the muscle cells on the distal portion of 
the gland are attached at the intercalary region located at the 
base of the duct. Contraction therefore operates in two ways. 
It draws open the lower end of the duct and at the same time 
reduces the volume of the gland sac. At first only the granular 
secretion is expelled, but, as contraction proceeds further, many 
epithelial nuclei are carried away from the muscular wall and 
are forced up the duct along with the secretion (fig. 20). In 
several glands where almost all the secretion had been expelled, 
solid cores of nuclei were found in the ducts, having been forced 
