13 
ZOOLOGY, 
In swimming, the monad stretches out the whip-lash-like 
appendage called the flagellmn, which vibrates witli an un- 
dulating, whirling motion, and produces 
a peculiar graceful rolling motion of 
the monad. When the nionad is fixed 
the flagellum is used to convey food to the 
mouth, which lies between the base of 
the flagellum and beak, or ^Mip." The 
food is thi'own by a sudden jerk, and with 
precision, directly jigainst the mouth. 
^^If acceptable for food, the flagellum 
presses its base down upon the morsel, 
and at the same time the lip is thrown 
back so as to disclose the mouth, and 
then bent over the paiticle as it sinks 
into the latter. When the lip has ob- 
tained a fair hold upon the food, the 
flagellum withdraws from its incumbent 
position and returns to its former rigid, 
watchful condition. The process of de- 
glutition is then carried on by the help 
of the lip alone, which expands latterly until it completely 
overlies the particle. All this is done quite rap- 
idly, in a few seconds, and then the food glides 
quickly into the depths of the body, nnd is envel- 
oped in a digestive vacuole, whilst the lip assumes 
its usual conical shape and proportions." (Clark.) 
Some monads are attached by a slender stalk to 
the leaves and stems of aquatic plants, and these 
are usually collected into compound monads, sev- 
eral arising from a common stalk. In such cases 
the body with its nucleus nnd two or three con- 
tractile vesicles is surmounted by a delicate collar, 
out of which the lash (flagellum) projects. 
Monads multiply (1) either by self-division, or (2) 
by the production of great numbers of extremely minute 
germs. Hence the minutest of all beings reproduce from 
FiG.7. — Gregarina from 
the alimentary canal 
of a beetle. 1, young- 
er state, with a beak- 
hke continuation {a') 
of the head. 2, older; 
a, anterior end; 6, 
hinder part of the 
body; c, nucleus. 
Highly magnified. 
