332 
BULLETIN OF THE BUREAU OF FISHERIES. 
The difficulty seems to lie in the fact that any given reaction is the resultant of 
complex conditions, which can be regularly repeated only when those conditions remain 
uniform. The life of the lobster during all of its free swimming life is apparently one 
of incessant activity, whether swimming at the surface or at whatever distance below 
it, and at all times of the day or night. In the account of their reactions to light, which 
later follows, it will be seen that their behavior is very complex and very variable. Cer- 
tain responses may not only vary but even disappear altogether in consequence of 
changes in the organism or in the stimuli which affect it. Further, since the chromato- 
phores as well as the muscles of locomotion are under reflex control of the nervous 
system, it is not more surprising to find variations in the responsive behavior of the 
pigment cells than in the activities of the body as a whole. 
All that can be definitely said at present concerning the gay and plastic coloring 
of the larvae is that it is an expression of chemical and physical changes in the body, due 
to stimuli, some of which are unfavorable, and that they have no protective significance. 
If every larva remained pale while swimming at the surface in the daytime, and took on 
color only at night, which is not the case, there would be no reason for supposing that 
there was a relation between the origin of the habit and the protection which it afforded 
because of the vast indiscriminate destruction which all such larvae suffer at the hands 
of inanimate nature. That any such hypothetical protection would really count for 
nothing is further shown by the fact that the young lobster emerges at the fourth stage 
in a richly colored dress which renders it more conspicuous at the surface where it still 
swims than it would be if it remained colorless. For the continuance of the race a single 
lobster in the fourth stage is worth many hundreds in the first, and we should hardly 
expect to find nature at one moment using certain measures to protect life and at the 
next the same means for destroying it. 
Both the blue pigment of the blood and the yellow and red pigment of the chromato- 
phores, as already remarked, are lipochromogens, which are converted into lipochromes 
under a variety of conditions whether the animal is dead or alive. The stomach and 
liver are sometimes bright red, which recalls an observation by MacMunn, who con- 
cluded from spectroscopic evidence that in the lobster ( Homarus gammarus) the entero- 
chlorophyll of the liver might be carried to the hypodermis and converted into a 
lipochrome. 
Structure and habits . — The most striking habits of the little lobsters immediately 
after birth are their incessant and apparently aimless activity, their preying and fighting 
instincts, and their voracity, which invariably results in cannibalism whenever the food 
supply is insufficient or unsuitable and where the young are too closely crowded in either 
vertical or horizontal limits; their seeking or avoidance of light under the variable sum 
of all the conditions which influence their behavior; their unstable, vacillating movements 
in the daytime or when stimulated by strong light ; the total absence of the instincts of 
fear and concealment so clearly expressed at a later stage; their sharp vision for small 
floating particles at close range; their lack of precise discrimination, snapping up many 
inorganic particles or dead organic substances which are useless as food; their pursuit 
