‘374 Some Account of the Medusce 
fect notions of elementary bodies, to explain the origin of 
every substance found in the animal ceconomy, or the se- 
ries of changes which it undergoes! Nature has her own 
Jaboratory, and is capable, without any foreign aid, of 
preparing the ingredients necessary for her productions. 
That a deficiency of calcareous matter in the system is the 
cause of the absence of the shell, no one will deny; but 
that this depends on some internal state, and not on the 
privation of lime, may be shown by the following curious 
circumstance. A hen, which I kept for some experi- 
ments, had its leg broken in two parts. The fracture was 
carefuily bandaged ; three days subsequent to which, se- 
veral eggs destitute of shells were found on the premises. 
The ben had deposited no perfect eges, nor were there any 
other birds from which these yolks could have proceeded : 
I therefore conjectured that all the calcareous matter de- 
signed for the formation of the shell had been employed in 
the regeneration of the bone. We find a similar law ex- 
isting in the human species. The reunion of a bone frac- 
tured during a woman’s pregnancy is often delayed until 
her delivery; and it is well known, that, if the horns of 
a deer be broken at the rutting season, it is incapable of 
procreating its species. 
I remain, dear sir, with great esteem, 
Yours faithfully, 
Westminster. Joun Ayrton Panis. 
. 
LXV. Some Account of the Meduse of the Genus 
Equoree. By Messrs. Peros and Lrsuzur*. 
Equidem et his sensum inesse arbitror, qui nec animantium, neque fruti- 
cum, sed tertiam ex. utroque naturam hahent, urticis (Medysis) 
dico et spongiis.—Plin. Hist. Nat. lib. ix, p: 49. 
Sulstance.—1 ue substance of all the zoophytes in ques- 
lion presents at first sight the appearance of a kind of 
jelly more or less diaphanous; more or less consistent, and 
of varions colors, according to the particular species. 
With the exception of the lines, lamella and vessels which 
fringe the lower surface of the umbrella, the texture of 
this substance seems to be homogeneous, even when ob- 
served through a strong magnifying glass : in whatever di- 
rection we tear them or cut tliem, the appearance does not 
change, nor do we discover auy trace of internal vessels. 
* Annales du Muscum d'Hist. Nat. tom. xv. p. 41. 
So 
