DIGESTION AND ENDODERM OF LIMNOCODIUM, , roe 
These groups appear to have a spiral arrangement, more or less 
definitely expressed. In fig. 6 two thread-cells are represented 
with ejected filament, showing the series of six small barbs at its 
base. In fig. 4 an optical median longitudinal section of the 
tentacle is drawn, in order to show definitely the character and 
arrangement of the endoderm cells. The specimen from which 
the drawing was taken had been treated with osmic acid and 
picro-carmine. An actual transverse section of a similar ten- 
tacle is shown in fig. 5. The endoderm cells consist of a dense, 
highly-refringent substance, which is somewhat wrinkled by the 
action of the reagent. The nuclei are a little smaller than those 
of the gastric endoderm. In some cases a small amount of 
granular cell substance may be seen radiating from the nucleus, 
but the whole cell body otherwise has been metamorphosed into 
a homogeneous cartilaginoid substance. ‘There is no continuous 
lumen, although the cells are disposed in a single series around 
the axis of the tentacle, and leave, on shrinking, a small space 
where their adaxial surfaces should come into contact. This 
potential lumen appears not to be continuous, even in the speci- 
mens treated by reagents, and in living specimens it has no 
existence. 
A structureless lamella (Stutz-lamella) (¢) adheres closely to 
the endoderm cells. Subjacent to the ectoderm cells are the 
very fine transversely-striped muscular processes (d), which are 
developed on their inner faces, not only here but in the case of 
the subumbrellar ectoderm and of the ectoderm of the adum- 
brellar surface of the velum. 
