332 



EVENINGS AT THE MICKOSCOPE. 



lias suddenly shrunk up to a sixth part of its former 

 length, exchanging at the same time its smooth slender- 



ness and translucency for 

 a corrugated semi-opa- 

 city. I push the knob 

 aside with a needle's 

 point and thus destroy 

 its adhesion ; which done, 

 I take up the severed and 

 shrunken sucker, and lay 

 it in a little sea-water in 

 the live-box. 



STJOKL m. Under a power of 180 



diameters we see that the tube is composed of two 

 series of muscular fibres, the one set running length- 

 wise, the other transversely or annularly ; the former 

 by their contraction diminishing the length of the tube, 

 the latter diminishing its calibre. The muscular walls 

 are covered with a transparent skin, studded with round 

 orange-coloured spots, perhaps glandular, exactly simi- 

 lar to those we saw on the ex- 

 terior of the spines and Pedicel- 

 laria. 



Now, to illustrate the action 

 of these tubular feet, I must 

 again have recourse to the de- 

 nuded shell of a preserved 

 Echinus. Taking this globose 

 empty box into your hand, hold 

 it up against the light, looking 



P0EE8 OF uncniN. .j^ ^^ ^j^g jg^gg Ovi^GQ, which 



was once occupied by the mouth ; — you see that the 

 whole shell is pierced with minute holes — pores, which 



