920 NATURE AND LIFE. 
vu 
and undertook experiments. ‘‘ Having an opportunity,” 
he says, “to examine the shores of the ocean, which are 
crowded with a vast number of crabs, a creature something 
of the nature of crawfish, I could not escape the suspicion 
that philosophers were wrong in this matter, and common 
people right.” Réaumur took lobsters and crabs, removed 
one or several of their limbs, and shut up the creatures so 
mutilated in reservoirs communicating with sea-water, At 
the end of a few months he was astonished to find that 
new legs had taken the place of those that had been re- 
moved. He repeated his experiments with crawfish also,’ 
and described, with the precision which has given him re- 
nown, the mechanical method of these new growths. 
Thirty years later, Abraham Trembley, while walking 
near a lake at the Hague, remarked in it certain fine green 
filaments, provided with appendages, and looking like vege- 
tables. To learn whether he was really dealing with plants, 
he cut one of them into several bits. The separated parts 
soon reproduced each a complete whole, and these individ- 
ual wholes moved, changed their place, and seized insects” 
with their arms to carry them into their digestive cavities. 
They were fresh-water polyps, true animals. Trembley 
learned that, when one of these polyps was cut in two, the 
head reproduced the tail, and the tail the head. He cut 
two of them lengthwise, and joined them in a graft; in- 
stead of a polyp with eight arms, he had one with sixteen. 
A short time afterward Charles Bonnet repeated Trembley’s 
experiments on the reproduction of the polyp, and tried 
others on a fresh-water worm called the naiad. He re- 
marked that this worm, like the polyp, grows again those 
of its parts that are removed. He made like trials with 
the earthworm, and proved to his great astonishment that 
this highly-complex animal, which has so many rings, with 
delicate locomotive organs attached to each ring, which 
56) 
has, too, digestive and generative systems, etc., possessed 

