242 THE MICROSCOPICAL NEWS. 
after the minute inhabitants of the waters, and observing it in some 
respects to bear the semblance of a plant, and in others of an 
animal, he resolved, by cutting it to pieces, to satisfy himself which 
of the twain it was, and found by this trial, that each piece became 
a perfect body of the same form, exactly like that of which it only 
formed a part. This would have determined him to conclude it to. 
be a vegetable, had he not discovered in it at the same time a 
frequent change of figure, and a motion from place to place, a 
greedy appetite, and a singular dexterity in catching, mastering, 
and devouring its prey, although much larger and seemingly 
Fig. 60. 
stronger than itself; circumstances which could leave but little 
doubt of its true nature. 
Having satisfied ourselves that Hydra is a living animal, the 
first thing to be determined is its form and colour. But this 
wonderful little creature varies so much in its movements that it 
is difficult to ascertain the real shape at first sight, and the form of 
the body can only be determined when fully extended. They then 
vary from one quarter of an inch to one inch in length, according 
to their species, from the free end, numerous filaments which are 
often much longer than the body, spread out in graceful move- 
ments in search of food. Ifthe animal is touched, these threads 
or tentacles rapidly shorten, and it shrinks into a round gelatinous 
