548 ANTHON. [Vor. XIX. 
ance according to the degree of secreting activity. The cells 
of the czeca are evidently very active in secretion and exhibit 
many granular protrusions. In the longer ceca there is but 
a single layer of cells, while in the shorter ceeca there are two 
incomplete layers. (Figs. 17 and 18.) The cells of the 
shorter ceeca are evidently much more active and show many 
narrow-necked protrusions. These protrusions increase in 
size till the cell projects into the lumen; the connection between 
the cell and the protrusions constricts, and there results a 
separation of the spherical globule. After the globule becomes 
free in the lumen it loses its definite outline. (Fig. 19.) The 
globule is finely granular, but nowhere contains any sign of 
a nucleus, such as described by Needham (Zoological Bul- 
letin, 1897) in the digestive epithelium of the dragon-fly 
nymphs. The discharged portion of the cell represents but 
a small part of the whole and does not contain any trophic 
center. The secretion here differs from that of the larva of 
Ptychoptera as described by Gehucten (quoted by Packard, 
pp. 326-329) for the globule is constricted off and does not 
burst through the cell membrane. The process closely resem- 
bles that of Collembola, although there are no such marked 
changes in cell alveolation. (Folsom and Welles, in the Univ. 
of Illinois Bulletin, 1906.) Many protozoan parasites are 
found’ in the ceca, being often wedged in, as it were, between 
the cells. (Fig. 20.) 
Near the posterior termination of the ventriculus are four 
very small protruding pockets, the gastric ceca. (Fig. 21.) 
These pockets have not been described as occurring in the 
nearly allied form, Holorusia. The epithelium here is com- 
posed of two layers of cells and is very much convoluted. 
The cells are evidently most active and show many protru- 
sions and discharged globules. 
The termination of the ventriculus is marked by a pale 
transverse line and the four coiled Malpighian tubules pass off 
at this point. Each tube passes forward to the base of the 
ventricular ceeca and then turns backwards. In a cross-section 
the tubules show a ring composed of from two to six large 
