THOMPSON: METAMORPHOSES OF HERMIT CRAB. 
167 
figs. 52, 53). The cytoplasm is scanty and stains faintly; the 
nuclei are small, spherical, and prominent. 
The green glands cannot be found in sections of the first or 
second zoea stages. Some third zoeae show them, but they are 
without a lumen and almost wholly confined within the base of 
the antennae. These glands are, however, constantly present in 
fourth zoeae and each has the form of a bent tube, 0.2 mm. long, 
either simple or with two short, ventrally projecting diverticula at 
the proximal end. 
The glands of the glaucotlioe are relatively longer than those of 
the zoeae and extend out of the antenna vertically into the cephalo¬ 
thoracic cavity (pi. 9, fig. 51 ,{/(/). Their shape may be compared 
to a letter “ L ” ; the orifice being situated at the angle, and the 
proximal diverticula forming the shorter arm. About the time 
when the livers swing to the left as they pass toward the abdomen, 
the tip of the vertical limb of each green gland begins to grow back 
as a canal which lies closely appressed against the lateral wall of the 
cephalothorax until it reaches the region of the pericardium. Here 
the canals swing toward the midline of the body, meet one another 
beneath the pericardial septum, and fuse to form a nephrosac, 0.1- 
0.2 mm. long (pi. 8, fig. 40), which for a considerable period may 
retain an imperfect median partition as a remnant of its double 
origin. Toward the end of the glaucotlioe phase the nephrosac 
passes to its definitive position in the abdomen (pi. 8, fig. 42) and 
during the adolescent period attains to the larger proportions rela¬ 
tive to the surrounding structures which it has in the adult crab. 
The cells of the basal portion of these glands in all stages, and of 
the whole gland in the zoeae and glaucotlioe, have granular, homo¬ 
geneous cytoplasm, small, reticulate nuclei, and indistinct cell 
boundaries. But the canals and nephrosac from their first appear¬ 
ance show the adult histology. Though the bulk of the gland is. 
not sufficient for the production of canals and nephrosac without 
a multiplication of cells, no mitotic figures could be found, which 
recalls the condition of the liver cells during the changes in those 
organs, where the nuclei remained reticulate. But there the original 
bulk is ample to form the livers of the sixth stage through a remod¬ 
eling. In both series of specimens the tissues seemed perfectly well 
preserved. 
A shell gland is present throughout the zoea phase. It is lost 
