NOTES ON L.M.B.C. ASTEROIDEA. DAL 
of sections which I have examined lend no support to this 
view, there being no coagulum in these spaces. Here 
again my results confirm those of Durham. Besides 
being concerned in the distribution of nutrient material 
to the tissues the central plexus is, according to Cuénot, 
Prouho, and others, the seat of the production of the 
pigmented corpuscles which occur in the hemal strands, 
in the vessels of the water vascular system, and in the 
coelom. According to the first named author this function 
is also discharged by the brown bodies of Tiedemann and 
the Polian vesicles. However true this may be, I am not 
disposed to agree with his assertion that their histological 
structure 1s identical. The cells of which the tissue of 
Tiedemann’s bodies is composed do appear to be similar 
to those of the central plexus, but the ramified tubules 
which together form the lumen of these bodies have a 
well defined epithelial lining of cuboid cells, continuous 
with that of the circum-oral water vessel. 
NOTE ON THE HISTOLOGY OF THE TUBE FEET :— 
Some time ago, my attention was arrested by a state- 
ment on page 259 of Mr. G. J. Romanes’ interesting little 
work entitled ‘“ Jelly-fish, Star-fish and Sea-urchins,”’ to 
the effect that ‘‘each of the tube-feet is provided in its 
membranous walls with a number of annular or rine- 
shaped muscular fibres ;”’ and a little further on that ‘‘if 
the contraction of these fibres is strong, the tube shrinks 
up entirely, i.e.,1s retracted within the body of the animal.” 
On purely physical grounds the first of these statements 
seemed to me to be highly improbable; and being at the 
time unaware of the existence of Hamann’s description 
and figures of the minute structure of these organs, I set 
to work to investigate the question for myself, with the 
result anticipated. The muscular fibres account for rather 
more than half the thickness of the tubular portion of the 
