194 
animal, and especially its anterior end, be subjected to 
pressure, the yellow pigment seems to become diffused 
through the whole skin, and the yellow granules in the 
cells mostly disappear. Some of the pigment also exudes 
into the water. Later such a compressed anterior end 
becomes green, and this pigment resists solution in alcohol. 
The skin also contains numerous mucus-forming cells, by 
the activity of which the envelopmg tube is formed. A 
specimen which was deprived of its tube was found 
twelve hours afterwards enclosed in an elongate mass of 
mucus formed by the epidermis. 
The secondary annulation of the skin, which corres- 
ponds with that of the adult, is shown in many post-larval 
stages, except in the first two or three segments, where 
the annuli are less clearly indicated. The metastomial 
grooves are only faintly seen. They unite just behind the 
middle of the achetous segment, and are there continuous 
with a shallow mid-ventral groove which marks the 
position of the ventral nerve cord. 
The mouth is a crescentic or semi-circular aperture 
at the anterior ventral edge of the peristomium (fig. 58). 
The pharynx is protrusible, and bears small papille. It 
leads into the ciliated cesophagus, which bears the two 
glands, each of which is a sunple finger-shaped outgrowth 
of the gut, 25—45 mm. long, directed forwards, and 
showing in its posterior portion three or four slight 
internal ridges which are the precursors of the larger 
septa found im the glands of adults. The secretion of the 
glands is already present in the form of droplets, some of 
which are still in the glands, while others are in the 
posterior portion of the csophagus. The stomach is 
marked by elongate oval areas, between which are blood- 
vessels. Chlorogogen cells are present, but are only dis- 
tinguishable along the margin of the blood-vessels, and 
