174 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



discs until they unite and so form tlie gastrolith. Each disc become 

 one of the prisms of the gastroUth. 



On the fifth and on subsequent days, the gastroUth was perceptibly 

 thicker and more complete up to the eighth day, after which we did 

 not observe any increase in size, although the growth probably 

 continued. 



After the molt we found that the gastroliths are dissolved within 

 a few hours and that they may either remain in situ or fall into the 

 lumen of the stomach and be broken up during the process of disso- 

 lution. 



There proceeds pari passu with the dissolution of the gastroliths 

 a hardening of the gastric teeth, of the mandibles, and then of the 

 chelipeds and abdominal tergites. 



As soon as the gastroliths are dissolved the lobster attacks his 

 cast, beginning to eat the bristles and small parts and proceeding to 

 devour more or less of the harder parts. The newly molted lobsters 

 seldom seriously attack their sloughs within three or four hours, and 

 generally eat the greater part of the cast within tweh'e or eighteen 

 hours. 



These observations do not in the least contradict those of other 

 workers, but merely extend into a new field. They suggest the 

 following conclusions, which are somewhat contradictory to Her- 

 rick's theory of the function of the gastrolith. 



It seems improbable that the preparation for the molt, by a soften- 

 ing of the shell and by a corresponding deposition in the gastrolith 

 of the excess of lime from the blood, begins at or before the middle 

 of the period between the molts. 



The hardening of the gastric teeth and mandiljles before any other 

 skeletal structures, the hardening of the chelipeds, and the subse- 

 quent eating of the shell contribute to make us believe that the 

 gastroliths are a supply of lime reserved for the hardening of these 

 structures so that the relatively vast supply of mineral matter in the 

 cast and in other shells may be made available quickly for the 

 hardening of the new shell. 



