112 CHARLES DARWIN 



ble, with the truncate end upwards, a few inches above the 

 surface of the muddy sand. When touched or pulled they 

 suddenly drew themselves in with force, so as nearly or quite 

 to disappear. By this action, the highly elastic axis must 

 be bent at the lower extremity, where it is naturally slightly 

 curved; and I imagine it is by this elasticity alone that the 

 zoophyte is enabled to rise again through the mud. Each 

 polypus, though closely united to its brethren, has a dis- 

 tinct mouth, body, and tentacula. Of these polypi, in a large 

 specimen, there must be many thousands ; yet we see that 

 they act by one movement: they have also one central axis 

 connected with a system of obscure circulation, and the ova 

 are produced in an organ distinct from the separate indi- 

 viduals. 1 ' Well may one be allowed to ask, what is an indi- 

 vidual? It is always interesting to discover the foundation 

 of the strange tales of the old voyagers ; and I have no doubt 

 but that the habits of this Virgularia explain one such case. 

 Captain Lancaster, in his voyage 20 in 1601, narrates that on 

 the sea-sands of the Island of Sombrero, in the East Indies, 

 he " found a small twig growing up like a young tree, and 

 on offering to pluck it up it shrinks down to the ground, 

 and sinks, unless held very hard. On being plucked up, a 

 great worm is found to be its root, and as the tree groweth 

 in greatness, so doth the worm diminish ; and as soon as the 

 worm is entirely turned into a tree it rooteth in the earth, 

 and so becomes great. This transformation is one of the 

 strangest wonders that I saw in all my travels: for if this 

 tree is plucked up, while young, and the leaves and bark 

 stripped off, it becomes a hard stone when dry, much like 

 white coral : thus is this worm twice transformed into 



19 The cavities leading from the fleshy compartments of the extremity, were 

 filled with a yellow pulpy matter, which, examined under a microscope, 

 presented an extraordinary appearance. The mass consisted of rounded, 

 semi-transparent, irregular grains, aggregated together into particles of 

 various sizes. _ All such particles, and the separate grains, possessed the 

 power of rapid movement; generally revolving around different axes, but 

 sometimes progressive. The movement was visible with a very weak power, 

 but even with the highest its cause could not be perceived. It was very 

 different from the circulation of the fluid in the elastic bag, containing 

 the thin extremity of the axis. On other occasions, when dissecting small 

 marine animals beneath the microscope, I have seen particles of pulpy matter, 

 some of large size, as soon as they were disengaged, commence revolving. 

 1 have imagined, I know not with how much truth, that this granulo- 

 pulpy matter was in process of being converted into ova. Certainly in this 

 zoophyte such appeared to be the case. 



* Kerr's Collection of Voyages, vol. viii. p. 119. 



