236 BRITISH NULLIPORES. 



vivid and varied colours of many Nullipores, which retain 

 their hues only while they remain submerged, and become 

 white by exposure and bleaching. Some Nullipores are 

 purplish, others green, and others variegated, and the co- 

 lour is evidently primitive, and not derived from any sub- 

 sequent tincture. Neither can we account in this way for 

 their forms, for although very inconstant to any one type, 

 yet the Nullipores often shoot up in shrubby figures de- 

 pendant on no foreign props ; or they form globular masses 

 made up of sinuous folded laminae, which are too regular 

 to be built up from the unregulated sediment of agglutinat- 

 ed particles of lime. 



I believe that the Nullipores are endowed with life, and 

 M'ith a vegetative growth, but that they are not species. 

 They are, to my conviction, merely the calcareous basis 

 of Corallina officinalis modified by external circumstances, 

 and hindered from passing through the stages of its normal 

 developement. This conclusion, Avhich rests on many ob- 

 servations, I do not mean to support by instancing similar 

 arrests of growth in many Fungi, but these afford an apt 

 illustration of my meaning. When an agaric has germi- 

 nated under pressure, we know well that it will continue to 

 grow vigorously, but the result is a Rhizomorpha or a Hi- 

 mantia, — a woody reticulated, or a plumy fibrous, fungus ! 

 Under other circumstances, the agaric will stop without 

 developing a pileus ; and otherwise assume forms so odd, 

 that the parentage can only be guessed at. So with the 

 diffusive Corallina. When its shoots are torn off by the 

 waves, the base, continuing to live, grows thicker and becomes 

 studded with rounded knobs, whence one form of Nullipora 

 polymorpha : when its site is a soft calcareous rock, the basal 



portion often becomes amorphous and very thick without 

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