^STINGING SERIES 3453 



sive and defensive weapons, it is necessary to obtain some idea of the animals 

 which use them, these Cnidarians having departed less from the simple Coelenterate 

 type than have the Ctenophora, in which this type is much disguised. Imagine, 

 then, a long footless stocking, sewn up at each end. By thrusting one-half of this 

 stocking into the other half, there would be obtained a long bag with a double wall. 

 Suppose this bag fixed by its blind end to the ground, while the open mouth end 

 stood up in the air, to catch anything that fell into it, and then suppose that, close 

 round the mouth, the double wall grew out into arms or tentacles, which could 

 catch anything passing and draw it into the mouth, then we should have a structure 

 somewhat resembling the fundamental form of the Ccelenterata. But it must 

 further be supposed that the two woolen walls of the stocking are replaced by two 

 layers of living cells, so that the outer one forms the skin, which is armed with the 

 stinging cells, while the cells of the inner layer are hungry creatures waiting to 

 digest anything digestible which comes down into the bag. This is still not enough, 

 as the whole animal must be able to move its tentacles, and to stretch or contract 

 its body; so that between the layers there is a special gelatinous layer in which run 

 muscle and nerve fibres. Further, in order that the tentacles, when they seize a 

 passing animal, may have no trouble with it, but may be able to bring it to the 

 mouth as easily as possible, they are thickly covered with batteries of stinging cells. 

 But how, it may be asked, can we get the beautiful bell-shaped jellyfish from such 

 a creature? The imaginary animal just described was fixed to the bottom of the 

 sea, or to weeds and stones under water, and here it would grow. But there is a 

 law of life that, after a certain size has been reached, further growth does not add 

 to the animal's stature, but takes the form of buds, which may either be cast off as 

 eggs to hatch and develop elsewhere, or may remain attached to and branching out 

 from the parent animal. Both these processes take place in the simple Cnidarians. 

 Some branch and rebranch to form beautiful trees, or stocks, made up of living 

 animals. Now if all these animals were to drop eggs which fell to the ground to 

 grow up around the parent stock, so fast would they grow that they would soon be 

 killing one another through overcrowding. Hence it has come to pass that in 

 many forms only a certain number of the animals forming a stock produce eggs, 

 -and these are able to break away and swim off with their load of eggs, to drop them 

 far away. In this way, swimming bells have been produced, originally only as 

 -carriers for scattering eggs broadcast, just as many trees have arrangements for 

 scattering seeds as far as possible from the parent stem. From this beginning, 

 all the race of jellyfish appear to have sprung. The free-swimming life offered new 

 fields for catching food. Myriads of small creatures swim near the surface of the 

 water; the Cnidarian fixed to the bottom of the sea may stretch its arms in vain 

 for these, while the free-swimming bell can go among them and follow them 

 along the surface currents, feeding as it goes. Hence, while the eggs of many 

 jellyfish when dropped develop first into fixed tree-like stocks, which, when grown, 

 let loose another swarm of jellyfish, the eggs of others, as if to save time, as it were, 

 and impatient of the fixed tree-like stage, hatch out at once as young jelly- 

 fish, which rise at one bound to all the free-swimming privileges of their immediate 

 parents. 



