CORALS AXD CORAL MAKERS. 15 



is afterward worthless ; for the tube cannot be returned to 

 tlie sheath. But those thus expended are not missed, as the 

 ])olyp has indefinite suppUes of such weapons, and also ready 

 means of refurnishing itself 



Figures 6, 7,8, 9, 10, pp. 14, 15, illustrate different stages in 

 the development of a lasso-cell (figure ro) out of a com ^^m 

 mon spherical cell, as made out by Dr. Mobius in his j^B 

 careful microscopic investigations. The Actinia afford- IH^ 

 ing the results was the Urticina crassicornis, found in ■^|i 

 both European and American seas. The actual size of B|y 

 the cell represented in figure 6 is about a 5000th of an K^ 

 inch. In figure 7 the lasso-cell has already taken form 1^9 

 but is folded on itself; in 8, there is a second infold- iBI 

 ing ; 9 shows a return to a single fold, and further ^SA 

 progress in the forming cell; and 10, the straightened- Wtm 

 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 ot 

 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 ex- 

 tended from the body through some natural orifices near the 

 base of the Actinia (especially those of the Sagartia family), 

 (iosse 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. 



