34 CORALS AND CORAL ISLANDS. 



out of a common spherical cell, as made out by Dr. Mobius in 

 his careful microscopic investigations. The Actinia affording 

 the results was the Urticina crassicornis, found in both Euro- 

 pean and American seas. The actual size of the cell represent- 

 ed in figure 6 is about a 5,000th of an inch. In fig. 7 the 

 lasso-cell has already taken form but is folded on itself; in 8, 

 there is a second infolding ; 9 shows a return to a single fold, 

 and further progress in the forming cell ; and 10, the straight- 

 ened lasso-cell. Thus the work of replenishing, throughout 

 the body wherever lassos are used, is always going on. 



The radiating partitions or septa in the internal cavity 

 of the polyp have along the outer free edge what looks like a 

 slender white cord attached to it by a much convoluted or 

 mesentery-like membrane ; and this cord contains vast num- 

 bers of lasso-cells radiately arranged. These white cords 

 through the multiplied plaitings of the mesenteric membrane 

 have great length ; and they sometimes extend up through the 

 stomach and pass out of the mouth ; or they are extended in 

 loops through the walls wherever they may happen to be torn. 



There are often also bunches of somewhat similar white cords 

 full of lasso-cells appended to the septa, which are extended 

 from the body through some natural orifices near the base of the 

 Actinia (especially those of the Sargartia family). Gosse calls 

 these cords Acontia. They extend out usually two or three 

 inches, and sometimes six inches, and thereby widen much the 

 stinging range of an Actinia, both for the purposes of defence 

 and attack. 



Gosse, in his " British Sea- Anemones," gives the results of 

 some experiments with regard to the action of these lasso-cells 

 (cnidce), from which a few paragraphs may be here cited. 



" It has long been known, that a very slight contact with 

 the tentacles of a polyp is sufficient to produce, in any minute 



