70 Composition of Eggs. 
art has already an Sapp ag of this substance. The following 
method enabled u ob the coloring matter as it exists in 
Crustacea, still es el pee green color 
The green coloring matter of Crustacea i is soluble in albumen ; 
besides, when Lobster’s eggs are crushed, the albuminous liquid 
which passes by filtering, is strongly colored green, and holds in 
solution the coloring matter. The ordinary methods, such as the 
action of heat, that of neutral solvents, desiccation, &c., which 
are applied to extract this singular substance, present it already 
_ modified. In fact, when alcohol or any other agent is used, the 
substance which till then, was green, instantly turns red ; but by 
— and for our work, very fortunate circumstance, tl ~ 
| 
fe) em perature. 
which have affinity for water can rranetal ‘m_the ie. coloring 
matter of Crustacea into a red substance: the st thei 
hand, which do not combine with water, exercise no acti 
this singular coloring matter. The action of a vacuum rapi 
produces the red color. Simple rubbing immediately reddens the 
green substance. Alcohol, ether, the acids, effect the same change. — 
There are not, to all appearances, in the vegetable or animal or- 
ganization, coloring substances comparable with this of the Crus 
tacea; modifying with such facility under the action of the 
simplest agents. We tried to determine whether this substauce — 
presented the same characteristics when still fixed in the shell ¢ 
Crustacea; the result of our experience is, that in this case, the 
green substance bears itself just as it does when isolated. ‘Thus 
a Crab’s shell, which shows the green discoloration, becomes 
the moment it is rubbed with a hard body. It is not the heat de- 
veloped by the rubbing which effects this singular rans 
for it has been effected while the shell was very damp, and be- 
sides, it is manifested rapidly on a Crab’s shell placed gine the 
receiver of an air-pump and submitted to the action of the vac’ 
uum. The change of color by rubbing explains how anatomisls 
who have sought for the cause of the discoloration of Crabs whe? 
boiled, have always seen the red matter under the coat, as thin 3% 
the epidermis which they removed to observe the shell under the 
microscope. The simple rubbing of the utricles, touched by the | 
scalpel, sufficed to make the green color red. We are fortunate 
