OMNIVOROUS ECHINODERMS, &c. 267 



whirlpool by which food is carried down into a ciliated funnel 

 at the bottom of which the mouth is placed, and through this 

 the nutritious particles, together with water, are conducted down 

 a short gullet into the soft interior of the body. The remaining 

 details are much as in the Slipper Animalcule. 



The Flagellata (see vol. i, p. 489) include a host of minute 

 creatures, many of which can only be studied by means of a 

 powerful microscope. Suitable examples are Euglena, Collar 

 Animalcules, and Monads. 



Euglena. — Stagnant pools, or puddles of fresh water, and 

 also the moisture accumulating in roof-gutters, are often of a 

 greenish colour, as a result of the presence of immense numbers 

 of Euglenae. Each individual is somewhat sausage-shaped, but 

 the writhing, worm-like movements which are constantly going 

 on alter its appearance from time to time. A long, quivering 

 flagellum projects from one end of the body, and at its base is 

 a minute mouth from which a short, funnel-like gullet projects 

 into the soft interior substance of the body. The flagellum 

 sets up movements in the surrounding water by which minute 

 food particles of various kinds are drawn into the mouth. 

 Euglena is green in colour, owing to the presence of green 

 pigment identical with that found in the leaves of ordinary plants. 

 There is also a red "eye-spot " near the front end. 



Collar Animalcules are simple or colonial forms, in which 

 each individual is comparable to a collar-cell of a sponge 

 placed on a stalk and leading an independent existence. As in 

 Euglena, small particles of food are drawn to the neighbour- 

 hood of the animal by the movement of the flagellum. Some of 

 these stick to the outside of the collar and are carried down to 

 a soft spot equivalent to a mouth. 



Monads are excessively minute Flagellates which swarm in 

 putrefying infusions. A typical species is the Springing Monad 

 [Heteromita), in which the body is pear-shaped and bears two 

 long flagella. One of these is directed forwards, and serves as 

 the active agent of locomotion, while the other is trailed behind. 

 This is one among very numerous cases in the Protozoa where 

 the food does not consist of solid particles taken in through a 

 mouth. In fact the Springing Monad would seem to be devoid 

 of a mouth, and feeds upon the nutritious substances dissolved in 

 the infusion where it lives, which are able to diffuse into the 



