536 A.. B. DAWSON 
usually lie at the outer surface close to the muscular layer. 
They are usually spherical or ovoid, but are sometimes greatly 
elongated and sometimes much flattened. They stain approxi- 
mately the same as the nuclei of ordinary epidermal cells, and 
show an irregular chromatin network with occasional large 
chromatin masses. No nucleoli were observed. A more com- 
plete account of the nuclei will be given in the description of 
the histogenesis of the granular secretion. 
The body of the mature gland in the resting condition is 
always found entirely full of the granular secretion, which, 
judging from the form of the gland, must be held under consider- 
able pressure. When expelled the secretion appears on the sur- 
face of the skin in small heaps. It is gray and does not flow 
readily. Fresh secretion examined with the microscope in 
normal salt solution is seen to be a liquid crowded with innumer- 
able globules which vary in diameter from 1 to 10 » and are not 
always perfect spheres. They are easily distorted under pres- 
sure, and if crushed they break down into very fine granules. 
The liquid in which the globules are suspended is colorless and 
somewhat viscid. 
The secretion is well preserved in 2.5 per cent formaldehyde 
or in a saturated solution of corrosive sublimate. The globules, 
when fixed, appear as large discrete granules, closely crowded 
‘ within the gland. In other fixing fluids (Kleinenberg’s, Gilson’s, 
Flemmings’s) the secretion presented an alveolar appearance 
with the alveoli filled with very fine granules. The disintegration 
of the large granules is without doubt due to the fixing agents. 
Arnold (’05) obtained much the same result with fixing fluids. 
But in the earlier stages of its elaboration, the granular secretion 
of Necturus is well preserved in all fixing fluids and always 
appears as distinct granules. Several other investigators have 
found difficulty in obtaining good preservation of the mature 
secretion, while they experienced no difficulty with the secretion 
in its early stages. In Triton, Nicoglu (’93) and Heidenhain 
(93 a) find that the granules fix readily till they attain a diameter 
of from 3 to 4 uw. After they become larger their appearance 
when fixed is greatly changed. 
