Extract of a Letter from J. F. Gronovius, M. D. at Leyden, November 1742 to Peter Collinson, F. R. S. concerning a Water Insect, Which, Being Cut into Several Pieces, Becomes So Many Perfect Animals

Duobus postremis anni mensibus complures repente occubuerunt, ex apoplexia alii, alii vero ex internis praecordiorum affectionibus. Illud denique animadversione dignum censemus, frequentes per aestatem, & autumnum fuisse morbos ex vermibus ortos, quos in acutis etiam vomitu, & dejectionibus expulsos vidi mus: idque in rusticis potissimum observare proclive erat. II. Extract of a Letter from J. F. Gronovius, M.D. at Leyden, November 1742. to Peter Collinson, F. R. S. concerning a Water Insect, which, being cut into several Pieces, becomes so many perfect Animals. SIR, Read Nov. 18. It is now about Nine Months since that a young Gentleman, living in the Family of Mynheer Bentinck at the Hague, discovered a Water Insect, not known yet or described by any Author. It has a pellucid Body, having here and there branched out something like Claws, with which it catches a particular sort of small Worms, which are every-where found in standing Waters: These are its Food. But of what Sort this Insect is, is not known; nor have its Mouth, Stomach or Intestines been yet discovered. But what is most surprising is, that, cut this Animal in Five or Six Pieces, in a few Hours there will be as many like their Parent. This Discovery was and is very surprising to all our Virtuoso's, and really not believed, until the Professors Albinus and Musenbrock were provided with the Animals, and, after having well examined this Creature, found the Prodigy of increasing itself in that wonderful Manner, very true. One of the Gentlemen that made this Discovery was Mr. Allemand, a Man of great Learning and Ingenuity, Tutor to the Sons of Mr. s'Gravensande. There The first Account given to the Royal Society, of this surprising Property of the fore-mentioned Insect, was in a Letter from Monsieur Buffon, of the Royal Academy of Sciences at Paris, and F. R. S. to Martin Folkes, Esq; now our President; his Letter bears Date the 18th of July 1741. N. S. and was communicated to the Society at their next Meeting on the 29th of October following; and therein Monsieur Buffon acquaints Mr. Folkes of Two very singular Observations lately made in Natural History; the First of a small sort of Bug, which produces its Like somewhat after the Manner of Plants, and without Copulation; the other of a small Insect called a Polypus, which is found sticking to the common Duck-weed, and which, being cut in two, puts out from the upper Part a Tail, and from the lower a Head, so as to become Two Animals instead of One; besides which, when cut in Three, the middlemost Part puts out from one End a Head, and from the other a Tail, so as to become Three Animals, all living like the first, and performing the Offices of their Specie. Both which Observations Mr. Buffon says were well averred. Mr. Folkes also at the same time communicated another Letter he had received from the Honble Charles Bentinck, Esq, at the Hague, dated the 15th of the foregoing September, wherein it is said, 'That a young Gentleman of Geneva, then in Holland, whose Name we since learn to be Monsieur du Tremblay, had found in Water, wherein he was looking for Insects, some small things he at first took for Plants, till, on a further Examination, he perceived them to move, and to contract themselves on their being touched; nor could he at first think them to be Animals, by reason of several young Shoots he found to come out from them, and to hang upon one another as far as the fourth Generation: He was, however, at last satisfied they were Insects, and that they preyed upon others, and would even eat raw Flesh. They fixed themselves, There have been several of these wonderful Creatures sent to Paris, to Mr. Reaumur, from whom we hope for a particular Dissertation. But after all, I do not think it a perfect Animal, but a kind of the *Uvae marinae*, *Holothuria* or *Zoophyta*, which really are living when they are first caught; of this Kind are the *Penna marinae*, figured by Barrelierus in Table 1273 and 1774, and also the *Fungi Marini*, Tab. 1293, 1294. These last I remember I have found several times on our Sea-Coasts, and observed that there was a living Nature in them. he said, by one End to some Plant, or the Side of the Vessel in which they were contained, and at the other End had Six or Eight Arms, with which they seized their Prey. He also found, that one of them being cut asunder, a few Days after, new Arms were grown out of that Part that had none before; since which he had cut them every Way possible, in Length, Breadth, and obliquely, and always with the same Success; after which he has gone on still further, subdividing them, but never found them to propagate any other ways than by Shoots, several at a time, and without any Copulation. Mr. Bentinck added, That this Gentleman would soon print an Account of the Observations he had made; and that the Insects he had himself seen of this Sort, were from about a Line to half an Inch in Length. The late Mr. Lewenhoeck seems to have met with this same Sort of *Animalcula* in the Year 1703, and has described and given a Draught of them in a Letter published in No 283 of these Transactions. Soon after which a more perfect Draught and Description of the same Insects were inferred from an anonymous Hand in No 288 of the same Transactions; all which Figures answer very well to the Description and a rough Sketch in Mr. Bentinck's Letter. In Fig. III. and IV. of this last cited Transaction, one of the Insects is represented as quite purlled up or contracted; but neither Mr. Lewenhoeck, nor the last-mentioned anonymous Author, ever thought of dividing the Insect, though the latter had observed the young Shoot dropping off from the Parent. III. Some