THE AMERICAN LOBSTER. 223 



has been excreted in the course of absorption of mineral salts from certain areas of 

 the shell. The subsequent assimilation of these bodies thus becomes of secondary 

 importance. It was found that small lobsters (3 to 4£ inches long) filled their stomachs 

 with fragments of dead shells of mollusks and Crustacea, probably for the purpose of 

 obtaining an immediate and abundant supply of lime for hardening the skeleton. 



(37) Hardening of the new shell. — From six to eight weeks are necessary under 

 ordinary conditions to produce a shell which is as hard as the one cast off, and lobsters 

 destined for the market are in better condition in from ten to twelve weeks after 

 molting. 



(38) Rate of growth. — From the data at hand we conclude that the rate of growth 

 varies considerably with the individual and its surroundings. The length of the 

 young lobster when it hatches from the egg is about 7.84 mm., and the increase in 

 length at each molt is about 15.3 per cent. The lobster molts from 14 to 17 times 

 during the first year. A lOi-inch lobster has molted from 25 to 26 times, and is about 

 5 years old. 



(3.)) Regeneration of parts. — All the appendages are capable of regeneration, the 

 time required for this process depending upon the time of the accident with respect 

 to the molting period and on the temperature of the water and the abundance of food. 

 Defensive mutilation or autotomy is perfectly developed only in the large chelipeds. 



(40) Size. — The greatest size attained by lobsters is about 25 pounds. This con- 

 clusion is reached after the examination of skeletons of large lobsters in museums and 

 comparing them with the measurements of large lobsters of known weight. Most 

 accounts of the weights of these animals are unreliable. 



(41) The weight does not bear a constant relation to the length, owing to the occa- 

 sional loss of the appendages. The large chelipeds alone contribute from one-quarter 

 to one-half the weight of the entire animal, and in giants like the Belfast lobster the 

 weight of the large chelipeds is more than two-thirds that of the entire body. The 

 weight is also subject to great variation in consequence of the molt, when a heavy 

 shell is exchanged for a much lighter one. 



(42) The adult male is as a rule heavier thau the adult female of the same length, 

 and this difference increases with age in favor of the male. 



(43) The egg-bearing females with eggs removed weigh less than the female lobster 

 of the same length without external eggs. 



(44) Enemies. — Every predaceous fish which feeds upon the bottom may be an 

 enemy of the lobster. The cod is one of the most destructive to small lobsters, after 

 the larval stages are passed. 



(45) Tegumental glands. — Besides the hair pores, the shell is perforated by innu- 

 merable minute pore canals which lead into tegumental glands situated in the soft skin. 

 Each gland has a capillary duct of its own which opens by a pore canal at the surface 

 of the shell, and each has one or two peculiar cells which resemble nerve or ganglion 

 cells. These organs are found widely diffused over the surface of the body, and they 

 also occur iu the walls of the oesophagus and intestine. It is probable that those in 

 the swimmerets of the female secrete the cement by which the eggs are glued to the 

 body, and that in some parts of the body, as in the labrum, they have a secondary sen- 

 sory function, and are the organs of taste, but this is uncertain. 



(46) Color. — The color variations of the lobster, some of which, like the red, blue, 

 and cream colored types, are nonadaptive, and this is also true of the remarkable color 



