332 BULI.ETIN OP 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 Ught, 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 Upochromes 

 under a variety of conditions whether the animal is dead or alive. The stomach and 

 Uver 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 prejdng 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 Ught 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 purstiit 



