4 



Lobsters turn 

 red in boiling 

 water. 



The epidermis is horny, and has feather-like hairs on certain portions of its 

 surface. The rete mucosum consists generally of pigmental matter diffused 

 through a certain thickness of the calcareous layer upon the corium; the 

 strength of the shell depends upon the calcareous material deposited in it,* 



Microscopally examined, the corium is found, in the crab, to be traversed by 

 parallel tubuli (like those of the dentine of teeth), giving off lateral branches 

 at certain regular distances. The best examples of the dentine-like structure 

 will be found in the black portion of the large claws. 



When lobsters are boiled, their armour-like coats turn red ; the coats of 

 crabs do not turn red with boiling. There is much doubt as to the cause of 

 this sudden change of colour by heat ; but, as far as I can ascertain, it takes 

 place in consequence of the decomposition of a peculiar substance which leaves 

 a red-coloured oil in a free state. This red-coloured oil does not appear after 

 contact with cold water, but appears instantly under the action of boiling water, 

 and gradually under the action of water slowly heated. It is highly interesting 

 to^observe the bright carmine hues running like a fire-work all over the coat, and 

 especially the eggs, of a dead lobster when water at 212° is poured upon it. 

 The beautiful colour which appears in the egg of the lobster is one of the 

 unfortunate reasons why so many millions of lobster eggs are so wastefully 

 consumed every year as a garnish for the white-coated turbot, or for fish sauce. 

 I have ascertained that spirits of wine has, as well as boiling water, the power 

 of changing the shell of the lobster and its eggs to this bright colour. It is 

 curious to observe that the eggs of a crab before it is boiled are of a red 

 colour, and they do not change their colour when boiling. 



When a horizontal section of one of the thin plates of an unboiled lobster's 

 tail is placed under the microscope a distinct hexagonal network can be seen, 

 This is found to be due to the presence of some innumerable granules of 

 calcareous matter which are in some places so angular as to lead me to believe 

 they are crystals of carbonate of lime. 



When a vertical section of a lobster which has been boiled is examined under 

 the microscope, both vertical and horizontal striae will be seen, the vertical 

 strise being the largest. The red colour can be distinctly seen not to be 

 contained in cells, but to consist of a finer and more compact tissue than the 

 other parts and to have the colouring matter equally diffused through it. 

 The reason why lobsters turn red when boiled and crabs do not turn red 

 requires further investigation both by chemists and microscopists. 



Crabs and lobsters contain much phosphorus ; the following table shows — 



Chemical com- The Chemical Composition of the Edible Parts of the Lobster. 



position of flesh 



of lobster. 



— 



Flesh. 



Soft Internal 

 Matter. 



Spawn. 



Nitrogenous matter - 

 Fatty matter - 

 Mineral matter - 

 Non-nitrogenous matter and loss 

 Water - 



19-170 

 1-170 

 1-823 

 1-219 



76*618 



12-140 

 1-444 

 1-749 

 0-354 



84-313 



21-892 

 8-234 

 1-998 

 4-893 



62-983 





100-000 100-000 



100-000 





! 



That phosphorus exists in large quantities in lobsters may easily be proved. 

 A lobster in hot weather, when it ceases to be fresh, asoumes a highly phospho- 

 rescent appearance when seen in the dark, equal, if not superior, to that of a glow- 

 worm or luminous centipede. This light increases by friction. Once in my life I 

 was called on to exorcise a ghost, which appeared in a phosphorescent form. The 

 ghost turned out to be a mass of bits of lobster and lobster shells thrown away into 

 a dark corner by the college cook. This phosphorescent appearance is probably 



* See Catalogue, Royal College of Surgeons, 

 Association, 1844 and 1847. 



'■ Histology," and Carpenter's Reports to British 



