304 THE OCEAN WORLD. 



the head of a \iilture ; but the lower mandible can be opened 

 much wider than a real bird's beak. The head itself possesses con- 

 siderable powers of movement, by means of a short neck. In one 

 polyzoon the head itself was fixed, but the lower jaw free ; in another 

 it was replaced by a triangular hood, with a beautifully-fitted trap-door, 

 which evidently answered to the lower mandible. In the greater 

 number of species each cell was provided with one head, but in others 

 each cell had two. 



" The young cells at the end of the branches of these polyzoa 

 contain quite immature forms, yet the vulture heads attached to 

 them, though small, are in every respect perfect. When the animal 

 was removed by a needle from any of the cells, these organs did not 

 appear to be in the least affected. When one of the vulture-like 

 heads was cut off from a cell, the lower mandible retained its power 

 of opening and closing. Perhaps the most singular part of their 

 structure is, that when there are more than two rows of cells on a 

 branch, the central cells were furnished with these appendages of 

 only one-fourth the size of the outside ones. Their movements 

 varied according to the species ; but in some I never saw the least 

 motion, while others, with the lower mandible generally \vide open, 

 oscillated backwards and forwards at the rate of about five seconds 

 each turn ; others moved rapidly and by starts. When touched with 

 a needle, the beak generally seized the point so firmly that the whole 

 branch might be shaken." 



Moreover, in Cresia, Darwin observed that each cell was furnished 

 ^nth a long-toothed bristle, which had the power of moving very 

 quickly ; each bristle and each vulture-like head moving quite inde- 

 pendently of each other ; sometimes all on one side, sometimes those 

 on one branch only moving simultaneously, sometimes one after the 

 other. In these actions we apparently behold as perfect a trans- 

 mission of will in the polyzoon, though composed of thousands ot 

 distinct animals, as in any individual animal. " What can be more 

 remarkable," he adds, " than to see a plant-like body producing an 

 egg, capable of swimming about and choosing a proper place to 

 adhere to, where it sprouts out into branches, each crowded with 

 innumerable distinct animals, often of complicated organisation — 

 the branches, moreover, sometimes possessing organs capable of 

 movement independent of the animals !" 



The prey which is drawn into the vortex by the tentacles and their 

 cilia enters into the mouth, to which is attached a pharynx, oesophagus, 

 stomach, and intestines. In the haemal region, not far from the mouth, 

 there is a special opening for the intestine. 



