THE society's NOTE-BUOKS. 3U1 



The slides of Si)onges and Spongillae are most interesting. 

 Going through a series of locally collected sponges with a friend 

 at Ramsgate a few weeks ago, we could neither of us determine 

 whether the axis of the bi-rotate spiculae are hollow or no (slide 

 No. 4), a bright spot in the centre of the radiating points seeming 

 almost to indicate this. Perhaps members working with higher 

 powers can determine (my highest power is 3^-in. with B eyepiece). 



J. Lucas. 



Observing the transverse section of the Burrowing Anemone 

 with a i-inch objective, observe the three body layers — ectoderm, 

 mesoderm (stained crimson in the section), and endoderm. The 

 ectoderm contains the stinging cells, or nematocysts, with which 

 the anemone paralyses and kills its prey. The mesogljea is com- 

 posed of muscular tissue ; the endoderm tines the entire body- 

 cavity in all its chambers with a coating of ciliated cells. Note 

 the oesophagus (the round circle in the middle). In this specimen 

 the section has been slightly crushed by pressure of the cover-glass. 



Notice also the short, pouch-like outgrowth from the oesopha- 

 gus ; this is the siphunoglyph. Most anemones have two of these, 

 but Peachia has only one. These siphonoglyphs are angles which 

 bound the extremities of the mouth-slit ; they are continued down- 

 ward into the oesophagus as deep, richly ciliated grooves, and 

 remain open even when the animal is greatly contracted. They 

 appear to be useful in keeping up a constant flow of water through 

 the oesophagus. 



Note also the twelve mesenteries which serve to break up the 

 great body-cavity into a number of radial longitudinal chambers. 

 These mesenteries are arranged in pairs; some reach across to the 

 oesophagus, and are called primary mesenteries ; others fall short 

 of it, and are called secondary mesenteries. 



Observe the ridges on one face of the mesenteries, and notice 

 in the section muscle fibres forming a beautiful arborescent pat- 

 tern. These are the muscles which pull down the tentacles and 

 mouth disc, so as to shorten and retract the animal. The accom- 

 panying rough illustration may serve to explain these remarks. 



Unsigned. 



