296 COLLECTING SEA-WEEDS. 



irregular patclies, which continually increase from 

 the circumference, in concentric zones. This is the 

 young state of the Corallina officinalis^ which by and 

 by shoots up into little bushes of many jointed twigs, 

 diverging on every hand, or hanging in tufts over the 

 edges of the rock-pools. Young collectors are eager, 

 I perceive, to seize such specimens as are purely 

 white ; but this condition is that of death ; in life 

 and health the shoots are of the same pale pm^ple hue 

 as the lichenous crust. This plant in both states (for 

 plant it undoubtedly is, though principally composed 

 of lime, and of stone-like hardness) is suitable for a 

 tank, as it survives and flourishes long; and your 

 pieces of rock-work you may select from such places 

 as are covered with the purple crust. 



The most valuable plant of all for our purpose is 

 the Sea Lettuce [Ulva latissima). Every one is 

 familiar with its broad leaves of the most brilliant 

 green, as thin as silver-paper, all puckered and folded 

 at the edge, and generally torn and fretted into holes. 

 It is abundant in the hollows of the rocks between 

 tide-marks, extending and thriving even almost to 

 the level of high water, and bearing with impunity 

 the burning rays of the summer's sun, provided it be 

 actually covered with a stratum of water, even though 

 this be quite tepid. It therefore is more tolerant than 

 usual of the limited space and profuse light of an 

 Aquarium, where it will grow prosperously for years, 

 giving out abundantly its bubbles of oxygen gas all 

 day long. It is readily found; but owing to the 

 excessive slenderness of its attachment to the rock, 

 and its great fragility^ it is not one of the easiest to 



