HYDEJE, OR FRESH- WATER POLYPES. 
275 
grow; it detaches itself from its mother, and differs not at 
all from any other polype. I have kept several of these 
polypes, and they and their young ones have multiplied in my 
glasses.” 
The following letter addressed by Baker to Mr. Martyn 
Folkes, President of the Royal Society in 1743, describes an 
attempt he made to turn a hydra inside out : — - 
July 6th, 1743. —Having learned, by one of Mr. Trembley’s letters which 
you, Sir, received after the preceding experiment, and was pleased to favour 
me with a sight of, that his method for preparing a polype for turning inside 
out is by giving it a chrysalis of the Water-Tipula, which, when swallowed, 
distends the polype's stomach and body, and having some degree of hardness, 
enables him, by gently pressing it from the tail upwards towards the mouth, 
and at the same time pushing the tail behind, to return it back again through 
the mouth along with the tail and body, and thereby Completely turned it, — 
I was desirous of doing the same thing ; but being unable to procure any 
such chrysalis at London, I fancied that perhaps I might perform this opera- 
tion by other means, though somewhat in the same manner. I fixed my eye, 
for this purpose, on a very large polype of the long-tailed sort, with only six 
arms, that had no young ones issuing from it, and gave thereto one of the 
biggest worms I could get, the whole whereof I was certain it could not pos- 
sibly swallow. The polype seized the worm immediately, and in less than a 
quarter of an hour had gorged as much of it as its body was able to contain, 
leaving one-third part at least hanging from its mouth. Things succeeding 
thus far to my wish, I loosened the polype’s tail from the side of the glass, 
took it out with a scoop-pen, and put it on a wetted slip of paper ; for I 
judged it best not to remove it before it had swallowed the worm, lest it 
should refuse to eat afterwards. This done, I set myself to work with a 
great deal of care and gentleness ; and fixing my paper whereon the polype 
lay by a pin to the writing-desk where I sat, I took hold of the worm by 
means of a pair of nippers which I held in my right hand, and at the same 
instant thrusting against the polype’s tail with the head of a very small pin 
(the point whereof I had previously fastened into a piece of stick, which 
served me for a handle to guide it by), I proceeded cautiously and leisurely ; 
and after several trials with the worm and pin, what by pulling one and 
thrusting with the other, the stomach, wherein part of the worm lay folded, 
came along with it through the mouth, and was followed by the tail, pin 
and all ; so that the polype was really and completely turned, though the 
pin had made a hole quite through it, contrary to my intent, and would have 
injured it much more, or perhaps unturned it, had I pulled it back the same 
way it entered in ; but, being aware of that, I unfixed the pin from the 
stick, took hold of it with my nippers (the polype being spitted as it were 
upon it), and pulled it away by the head, leaving the polype fairly inside 
out. 
The following species kave been described as belonging to 
tbe British fauna : — 
Hydra viridis ; of a beautiful grass-green colour tentacles 6 to 
