62 REPORT OF COMMISSIONERS OF INLAND FISHERIES. 



first stage, are much more active at night, as evidenced by the splash- 

 ing and beating within the cages of the adult lobsters, which by day 

 lie quietly at the bottom; or by the restless crawling of the young 

 adults among the pebbles and shells of their glass dishes, as soon as 

 night has fallen; or by the more active swimming of the j^'oung larvse 

 at night about the glass cylinders in which they were observed. 



To the results of many of these experiments appeared some con- 

 tradictory facts, as for example, — on a dark and cloudy day vast 

 numl^ers of young larva swimming about the bags evinced red 

 pigmentation to a high degree. Not only this, but in the case of 

 many large adult lobsters, floating in cages at the surface where they 

 were exposed to the direct sunlight, their red coloration to a large 

 degree was lost and the color became a brilliant blue often variated 

 by leopard spots or mottlings. The normal color was not regained 

 after some specimens had been sunk to the bottom of the harbor for 

 a period of three weeks. It should be noted, however, that this 

 change was not due to a disturbance of the chromatophores, but to 

 some chemical change in the pigments of the exoskeleton. 



IV. Pigmentation of the Fourth and Later Stages. 



Fourth Stage. 



As has been stated on a previous page, when the lobster moults 

 into the fourth stage there may be a wide variation in color and 

 color patterns, but when once assumed there is, with a few exceptions, 

 a constancy to this type throughout the stage, and often enduring 

 into successive stages. The phenomenon of rapid and transitory 

 color changes so characteristic of the first three larval stages is no 

 longer present. 



In the color scheme of this stage we may note three varieties: (1) 

 yellow, (2) red, (3) green. These terms designate the color types in 

 wliich the stated color is predominant, but in which there ma}' be 

 many modifications; for instance, a yellow lobster may and usually 

 does show in certain areas no small amount of red pigmentation, and 



