THREAD-CAPSULES. 



107 



some resemblance to that which is felt when the 

 finger is thrust into the mouth of the common 

 ringed snake, or of several fish. The mode of 

 adhesion is only to be discovered by the aid of 

 a tolerably powerful microscope, and when dis- 

 covered is found to be equal in beauty to any 

 structure that is yet known. 



Scattered at intervals over various portions 

 of the body, and especially crowded on the ten- 

 tacles, are found tiny organs that are called by 

 the name of thread-capsules. These are little 

 oval vesicles, imbedded in the substance of the 

 anemone, and containing within them a long 

 delicate thread, closely coiled, in forms varying 

 according to the description of capsule. The 

 extreme tenacity of the thread may be imagined 

 from the fact that the largest capsules are not 

 more than the three-hundredth of an inch in 

 length, and that within so small a compass the 

 thread is coiled like a watch-spring in the barrel. 

 Indeed, the simile of a watch-spring will nearly 

 express the object, for the thread is so strong, in 

 spite of its tenuity, that it has aptly been com- 

 pared to the hair-spring of a watch. When the 

 tentacles are irritated or compressed, myriads of 

 these capsules start forward, become everted, and 

 shoot forth their tiny spears. The length and 



