go EDWARD POTTS : 



the place of support, and there to attract many of the lower 

 Protozoa, Rhizopods, Trachelomonads, etc., to enjoy this 

 " predigested food," and, adding to it their own remains, 

 they together form quite a serious obstruction to a perfect 

 view through a microscope. 



To the presence of minute living Protozoa, Microliydra 

 seems entirely indifferent, but when Rotifers of a rather larger 

 size begin to browse over their bodies, we notice the first 

 evidence of sensibility, at least in the upper third of its length. 

 As soon as that height is reached, it has been observed that 

 the capitulum is deliberately curved toward the enemy (or 

 the desired victim) and, if it happens to be particularly 

 stupid, the trespasser is caught and swallowed ; but if, 

 alarmed, it turns away, the capitulum is also returned to its 

 former position of watching. The point I make is this, and 

 it is a first step towards explaining the mystery, heretofore 

 felt, as to its ability to catch its prey. It has not been actu- 

 ally seen, but is clearly inferred, that the moistened, everted 

 lips, shown in one of Dr. Ryder's drawings, lick up, as it 

 were, the small prey and draw it into the beginning of its 

 downward course. 



AS TO ITS FOOD. 



It is now found necessary to change entirely the descrip- 

 tion heretofore given of the nature of this hydroid's food 

 supply and the method by which it is captured. I have gen- 

 erally compared it to a starveling dog with open mouth 

 catching at any crumbs that might fall from the rich table 

 spread above it by its abler-bodied neighbors. That must all 

 be taken back, and you may now picture it, not as snapping 

 at crumbs, but, as a Scriptural passage says of a very different 

 animal, " The young lions do roar after their prey, and seek 

 their meat from God." I have never actuall}' heard it roar, 

 to be sure, but have no doubt the source of its supply is the 

 same as is the others'. It is no longer hungry and snarling, 

 as a dog over a just discovered lione, but vigilant and 



