INTEGUMENT OF NECTURUS MACULOSUS Dad 
In his description of the development of the poison granules 
in the glands of Salamandra maculosa, Nirenstein (’08) dis- 
tinguishes two stages in the formation of the secretion. In the 
first stage the granules are ‘albuminoid’ in nature, coagulate 
readily in all fixing fluids and retain their spherical form. In 
the second stage the specific poison, salamandrin, is elaborated 
and the granules do not retain their form in fixing fluids. The 
secretion when mature is surrounded, he believes, by a semi- 
permeable membrane, and in fixing solutions the alkaloid poison 
diffuses out and the granule is thus destroyed. 
In Necturus the changes in appearance between the immature 
and the completely elaborated secretion are not so striking as 
those described by Nirenstein, but the fact that the secretion 
in different stages of development does react differently to the 
same fixing fluids indicates cearly that there is a change in its 
chemical composition. In all its stages the granular secretion 
takes ordinary plasma stains very readily and the glands always 
have a decided color. ‘The secretion mass is colored red or dark 
purple in Mallory’s and yellow in van Gieson’s stain. The 
granules are never colored in such basic stains as iron haema- 
toxylin, Ehrlich’s or Delafield’s haematoxylin, thionin, or methy- 
lene blue. However, Heidenhain (’93 a), Nicoglu (’93), Esterly 
(04), Arnold (05), and Nirenstein (’08) find that the granules 
of this type of gland stain black in iron haematoxylin. No 
experiments were attempted to prove whether or not the granular 
secretion was poisonous. 
g) Epithelium and secretion of the mucous gland. In con- 
trast with the granular glands, which act as reservoirs -for secre- 
tion, the mucous glands (figs. 6, 12) in the majority of prepara- 
tions are seen to be actively discharging secretion onto the 
surface of the epidermis. In many Amphibia they have been 
described as consisting of a single layer of secreting cells sur- 
rounding a capacious lumen, but in Necturus the secretion occu- 
pies the entire body of the gland and the secreting epithelium is 
greatly reduced. Cell limits are seldom perceptible, and the 
small, irregularly shaped, and densely stained nuclei are scattered 
unevenly over the wall of the gland. No cytoplasm can be 
