THE MICKOSCOPIST IN BERMUDA. 127 



composing matter ; and that these minute creatures, which are in 

 reality the peculiar food of the polyzoa, are drawn into the mahl- 

 strom which the tentacles are continually creating in the immed- 

 iate vicinity. If this is the true explanation, and it seems 

 somewhat probable, we have here a strange and altogether anom- 

 alous provision for the feeding of these ever stationary colonies. 

 The question then naturally arises : how came these singular 

 members to be jointed to the cells of certain genera of Polyzoa, 

 and to be endowed with the instinct of catching prey that their 

 masters never ate? 



The general theory of evolution is that an organism lays hold 

 of all the slight modifications of structure which are in anywise 

 useful to it, and by perpetuating them through inheritance, 

 eventually comes to possess the perfected organs or peculiarities. 

 But in the case we have presented, you will doubtless agree with 

 me that nothing less than a perfect seizing instrument and a fully 

 acquired habit of holding on to its captures until they died and 

 decomposed, would be of any use at all to the polyzoan animal. 

 There can be no intermediate links no less useful processes for 

 natural selection to lay hold of. We must therefore suppose that 

 these remarkable appendages sprouted out at once and all perfect, 

 as a sport of nature; or else that they grew upon the animal 

 without cause or provocation. For myself I hold to the opinion 

 that we have not yet begun to fathom the depth of nature's plans 

 in the matter of perfecting its great families and orders of 

 organisms. 



There is often thrown upon the sea shore some matted tufts of 

 fibers which look like clusters of fine sea-mosses. But the micro- 

 scope shows at once that they are of animal origin and built up 

 by the budding out of successive polyp-like animals one above 

 the other. They have much the appearance of the Polyzoa just 

 described, but are built up on a larger and coarser pattern, and 

 are really of an entirely different family. They are the Hydro- 

 zoa, nearly at the bottom of the scale of animal life, with a 

 simple sack stomach, and scarcely another organized structure in 

 their systems. But they exhibit in their manner of reproduction 

 the most characteristic example of what is called the alternation 



