70 



LIFE, IN ITS LOWEB FORMS, 



pleasure of the animal, or under the stimulus of pressure, 



the thread is shot forth from one end of the cell with great 

 force, until it extends to a length from twice to fifty times 

 that of the cell. When fully extended, it is seen that the 

 thread is but a continuation of the cell itself ; that when it 

 was dormant, it was turned in ; and that in the process of 

 expulsion, every part of its length has actually been turned 

 inside out, like the finger of a glove. Sometimes the 

 thread appears simple, but in those cases in which a cham- 

 ber appeared within the cell, it is furnished with an 

 armature of barbed threads, which after expulsion pro- 

 ject from the sides of the thread in various directions. 

 The propulsion of the thread is sufficiently forcible to 

 enable it to enter the tissues of other animals, and the 

 barbed structure enables the weapon to retain its hold in 

 the flesh, which facts warrant the presumption that a 

 highly poisonous fluid is at the same time injected, capable 

 of arresting and destroying animal life. Some of the forms 

 of these organs are represented in the accompanying 

 figures. 



In captivity, the process of taking food may be witnessed 



