324 REPARATIVE POWERS OF LOWER ANIMALS, 
Of certain kinds of Holothuria (fig. 67), which eject the entire 
mass of viscera under the influence of alarm, it has been ob- 
served that they not only continue to move about as if nothing 
had happened, but that, under favourable circumstances, they 
regenerate the whole of the digestive and reproductive appa- 
ratus thus parted-with.—Next to Zoophytes, there are no 
animals in which the regenerative power is known to manifest 
itself so strongly as the lower members of the Articulated 
series, such as the inferior Hntozoa and the Z'urbellaria (Zoo- 
Loey, § 924), among which last we find the Planaria almost 
rivalling the Hydra, although it is an animal of much more 
complex structure. The common Larthworm can reproduce 
either the head or any portion of the body of which it may 
have been deprived; but it cannot be multiplied by the division 
of its body into two or more parts (as asserted by some), since 
these parts, although they continue to move for a time, soon 
perish. There are Worms allied to it, however, in which the 
regenerative power is sufficient to produce the whole body 
from a separated fragment; and no fewer than twenty-six 
have thus been made to originate by the subdivision of a 
single individual. In the higher Articulata, such as Crus- 
tacea, Insects, and Spiders, the reparative capacity is limited 
to the restoration of limbs; and even this would seem to be 
seldom preserved in perfect Insects, being restricted to the 
larval period of their lives. Little is known of the regene- 
rative power possessed by the higher Mollusks ; but it has 
been affirmed that the head of the Snail may be reproduced 
after being cut-off, provided the cephalic ganglion be not 
injured, and an adequate amount of heat be supplied. 
390. It is only among the cold-blooded members of the 
Vertebrated series, that the reparative power extends to the 
renewal of entire organs ; and this seems limited in Wishes to 
the reproduction of portions of the fins which have been lost 
by disease or accident. In Batrachia, however, it has been 
found that entire new legs, with perfect bones, nerves, 
muscles, &c., may be reproduced after severe loss or injury 
of the original members ; and even a perfect eye has been 
formed in place of one that had been removed. It is inte- 
resting to observe that the exercise of this reparative power 
essentially depends upon the temperature in which the animal 
is living; the reproduction of entire members apparently 
