92 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



oesophagus. According to Mayer, whom Roesel quotes with some reserve, it was the 

 custom of the inhabitants of Asiatic Tartary and Ukrania to collect crayfish at the 

 time of the year in which they were in the best condition and place them in large pits 

 in the ground. Here they were broken up and allowed to remain all winter, during 

 which time the evil odor kept everybody away. In the spring the owners would 

 return, wash out the remnants of the crayfish in water, and sift out the stones with a 

 sieve which they used for this purpose. It was formerly the custom also in Poland 

 and Russia, on the River Don, to collect crayfish in large quantities and allow them 

 to rot in the fields or in pits. The stones were afterwards carefully collected and sent 

 to market to be used as medicine. 



Mr. Baker (7) communicated to the Royal Society on February 25, 1748, an inter- 

 esting letter on "crabs' eyes" from Dr. James Mouusey, a Russian physician. He 

 noticed the seal-shaped spots on the wall of the stomach, which mark the position of 

 the developing gastroliths, and concluded that the latter helped to form the new shell, 

 which, he says, " does not greatly recommend the opinion that these stones have a 

 dissolving quality of service against the stone in the human kidneys and bladder." 

 "The price comes to a groat or sixpence a pound. All the apothecary shops through- 

 out the whole Russian Empire are furnished with them, and great quantities are 

 exported." Notwithstanding their cheapness, "fictitious bodies, made of chalk" and 

 " tobacco-pipe clay " were cast in molds and substituted for real " crabs' eyes." In 

 this case the counterfeit undoubtedly possessed all the virtues of the genuine article. 



K. E. von Baer (6) thought that the gastroliths were salivary stones, developed 

 in the lumen of a salivary gland, an idea which was not destined to bear much fruit. 

 Some writers even pretended that they were cast out through a fissure in the walls of 

 the stomach and body. 



Van der Hoeven (195) seems to have been one of the first in the present century 

 to protest against the theory that the sole function of the gastroliths was to provide 

 lime for the new shell. In his Handbook of Zoology, a translation of which was 

 published in 1834, he says : 



The part, however, which the crabs' eyes take in the secretion [of the hard shell] can not he 

 great when we compare their weight with that of the calcareous matter of the shell. During the 

 time that the shell is still increasing in hardness no new crabs' eyes are produced; but only after 

 the shell has attained its greatest hardness is calcareous matter again secreted on the walls of the 

 stomach, and new crabs' eyes again appear. Thus the production of crabs' eyes would seem to be 

 a vicarious secretion of such constituents of the blood as, if too abundant, would be injurious to the 

 organs, like the secretion of urine for instance, but with this difference, that the calcareous matter is 

 not set at liberty shortly after its secretion, but remains accumulated for a long time in continuance. 



Max Braun, in his work on the molting of the crayfish (22), concluded that the 

 gastroliths were cuticular products analogous to the integument, but paid no attention 

 to their function or growth. 



Vitzou (197) says that shortly after the molt in the lobster the gastroliths are dis- 

 solved in the acids of the stomach and, entering the lymph, form an inorganic reserve 

 comparable to the phosphatic plaques which are found in the membranes of the foetus 

 in ruminants. 



The problem of the gastroliths has recently been attacked by Irvine and Wood- 

 head (105) in one of their valuable communications on the secretion of carbonate of 

 lime in animals. They conclude that, if the gastroliths play any part at all, they must 

 be converted into phosphates and thus carried in the lymph. If the brachyura have 



