196 Herbert W. Rand 
after having regained full extension. The diameter of the distal 
portion of the stump in many cases seemed markedly greater than 
the diameter of the corresponding region of the tentacle before it 
was cut, while the length of the extended stump was usually slightly 
less than the length of the corresponding portion of the uninjured 
tentacle. In full extension the distal end of the stump retained 
the hemispherical form and the projecting cylinder which we may 
conveniently designate as the nzpple. 
The color and general appearance of the tissue at the closed 
end of the stump deserve notice. The outer surface of a normal 
extended tentacle is marked by very narrow and somewhat irregu- 
lar transverse bands. ‘These bands are represented on the prox- 
imal portion of the normal tentacle on the right side of Fig. 2. The 
bands are whitish and opaque, and appear to be made up of more 
or less blended spots. Between these bands the tissue is of yel- 
lowish brown color and very translucent. When the tentacle con- 
tracts the darker colored translucent zones appear to contract 
more, and as a consequence the whitish parts are so crowded 
together that the bands become less conspicuous or even quite 
indistinguishable to the eye. Therefore the contracted tentacle 
appears lighter colored and more opaque than the extended 
tentacle. The nipple upon the closed stump is whitish and 
densely opaque. The surface of the hemispherical wall which 
closes the end of the stump exhibits a gradation from whitish 
opacity to yellowish translucency. Immediately around the base 
of the nipple the tissue is whitish and opaque like that of the nipple 
itself, while, proceeding toward the equator of the hemispherical 
end, these two qualities gradually shade off into the yellowishness 
and translucency, respectively, of the lateral wall of the tentacle. 
(In the figures the opacity of the nipple and the region surround- 
ing it is indicated by the dark shading.) 
The cut end of the stump is functionally closed. In the nor- 
mal tentacle there is a certain amount of internal fluid pressure. 
By this gentle pressure the extended tentacle is kept full and 
plump, and the act of extending after a contraction is doubtless 
facilitated. When a tentacle is cut, so that the internal pressure 
is released, there follows instantly a collapse of the walls, which is 
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