NOTES ON L.M.B.C. ASTEROIDEA. 147 



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 Cuenot, 

 Prouho, and others, the seat of the production of the 

 pigmented corpuscles which occur in the haemal 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 is 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. Komanes' 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 ring- 

 shaped muscular fibres ; " and a little further on that " if 

 the contraction of these fibres is strong, the tube shrinks 

 up entirely, i.e., is 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 



