No. 15] MIDGUL OF THE TERRESTRIAL [SOPODS. 93 
through many cells (Fig. 12, v), appearing in surface prepara- 
tions like more or less extensive blisters of the epithelium. I 
at first thought they were artifacts produced by osmosis during 
the preparation of the gut for fixation, but preparations which 
were made from animals opened under corrosive sublimate, so 
that fixation of the tissue took place before any osmosis capable 
of producing such changes could occur, showed them quite as 
well as preparations from animals which were opened under 
normal salt solution. They undoubtedly exist in the living 
epithelium. Sections (Fig. 12) through a large vacuole of this 
type show that it is contained within the cytoplasm, the outer 
and inner layers of which are forced apart, the nuclei of the cells 
lying sometimes in the outer and sometimes in the inner layer, 
and usually showing greater or less signs of compression. The 
supporting fibres in the area covered by the vacuole are broken 
across. 
In none of the literature to which I have access have I found 
the slightest reference to these blister-like vacuoles. The 
shaded area shown on the left side of Ide’s Fig. 19 (92) looks 
as if it might be one of them, but no reference is made to it in 
the text, and in the description of the figure it is said to repre- 
sent an area occupied by cells of a more columnar form than 
are found elsewhere. As has been noted, however, these vacu- 
oles are of much less frequent occurrence in Oxzscus and 
Porcellto, the genera most abundantly studied, than in Arma- 
atllidium. In Jdotea vacuoles extending through two cells were 
very abundant, but I found none at all comparable in extent to 
those of the land genera. 
Other products of metabolism are not abundant in Onzscus 
and Porcellio; occasionally one or two large spherical granules 
which stain a deep-red color with the Biondi-Ehrlich stain are 
to be found in some of the cells, and are probably metabolic 
products. In Avmadzllidium, however, the case is very differ- 
ent. In fully grown specimens of this genus very numerous 
granules of a greenish-yellow color are frequently found in 
every cell (Figs. 3, 5). They are scattered to a certain extent 
through the cytoplasm, but are always much more densely 
aggregated immediately below, 7.e., external to the nucleus, a 
