472 PHILOSOPHICAL TRANSACTIONS. [aNNO 1747-8. 



be in great plenty there ; and in the shops it is observable, that many of these 

 stones are of a brown hue ; which is the case of such as have been already lodged 

 in the cavity of the stomach, when the fish was taken. They likewise eat the 

 old shells immediately after shedding them.* What the use of these stones to 

 the creature is, he cannot positively determine, but supposes they may be designed 

 to furnish new petrescent juices to its fluids; which may be also assisted by the 

 old shells which they devour, the particles of which, as well as of the stones, 

 are probably disposed of, according to their degree of purity, and properly depo- 

 . sited at the extremities of vessels, for the reproduction of their annually new 

 crusty dress; which, he obsei-ves, does not greatly recommend the opinion that 

 these stones have a dissolving quality, of service against the stone in the human 

 kidneys or bladder.. 



The Doctor has sent along with this particular account, specimens of the craw- 

 fish both boiled and raw, which differ little or nothing from those catched in our 

 rivers here ; in which it is assured the like concretions may be also found at a 

 certain time of the year : he has likewise sent some of their stomachs dried, where 

 the stones appear, situated in the manner above described between the 2 coats ; 

 and in one of them they are got through the internal coat into the stomach it- 

 self. He also sent several specimens of the beginning scales, or concretions, of 

 different sizes, which he collected himself, in dissecting these creatures ; several 

 of the formed stones of his own taking out, some of a larger size, which were 

 given him by a gentleman, who took them out of the craw-fish in the river 

 Donne, and others still larger, which he chose from the apothecary of the army. 

 These last were from Astracan : and he observes that the fish and stones are 

 much the largest in the great rivers there, where there are fishers for craw-fish 

 on account of the stones only ; which they separate from the fish at different 

 fisheries after different manners. At some they are beaten to pieces with wooden 

 pestles ; then washing away the flesh and shells, the stones are found remaining 

 at the bottom of the vessel ; at others they are laid in heaps till they rot ; and 

 then being washed, the stones are easily separated and gathered. All the apo- 

 thecaries' shops throughout the whole Russian empire are furnished with them, 

 and great quantities besides are exported. 



This seems to be a very particular and exact account of these productions, 

 which are frequently prescribed in medicine. Their price, we find, is extremely 

 low in the countries where they are gathered ; and yet fictitious bodies, made of 



• I have, says Mr. Baker, observed the same thing in the small fresh water shrimp; which I have 

 kept in a glass with water throughout several of the periods of its casting its shell, which it does once 

 in about 4 or 5 weeks. The water newt also eats its skin as soon as palled off, if it be not taken 

 away. — Orig. 



