AYDRIDA. 121 
The third and most extraordinary mode of reproduction in the 
polyps has been discovered by Trembley in the case of the green 
Hydra. So surprised was this naturalist at the strange anomalies 
which surround these creatures, that he began to have doubts, and 
gravely to ask the question, is this polyp an animal? or, is it a 
plant? 
In order. to escape from this state of indecision, it occurred to 
him to cut a Hydra into pieces. Concluding that plants alone could 
reproduce themselves by slips, he waited the result of the experiment 
for the conclusion he sought. On the 25th of November, 1740, he 
cut a polyp into sections. “I put,” he tells us, “the two parts into 
a flat glass, which contained water four or five lines in depth, and 
in such a manner that each portion of the polyp could be easily 
observed through a strong magnifying glass. It will suffice to say 
that I had cut the polyp transversely, and a little nearer to the 
anterior. On the morning of the day after having cut the polyp, it 
seemed to me that on the edges of the second part, which had 
neither head nor arms, three small points were issuing from these 
edges. This surprised me extremely, and I waited with impatience 
for the moment when I could clearly ascertain what they were. 
Next day they were sufficiently developed to leave no doubt on my 
mind that they were true arms. The following day two new arms 
made their appearance, and, some days after, a third appeared, and 
I could now trace no difference between the first and second half of 
the polyp which I had cut.” 
This is assuredly one of the most startling facts belonging to 
natural history. Divide a fresh-water polyp into five or six parts, 
and at the end of a few days all the separate parts will be organised, 
developed, and form so many new beings, resembling the primitive 
individual. .Let us add, that the polyp which should thus have lost 
five-sixths of its body, the mutilated father of all this generation, 
remains complete in itself; in the interval, it has recuperated itself 
and recovered all its primitive substance. 
After this, if a Aydra vulgaris wishes to procure for itself the 
blessings of a family, it has only one thing to do: cut off an arm; 
if it desire two descendants, let it cut the arm in two parts; if three, 
let it divide it into three; and so on ad infinitum. “ Divide one of 
the animals,” says Trembley, “and each section will soon form a new 
individual in all respects like the creature divided.” “A whole host of 
polyps hewn into pieces,” says Frédol, “will be far from being 
annihilated.” ‘On the contrary,” we may say, in our turn, ‘“‘its 
youth will be renewed, and multiplied in proportion to the number of 
