REPORT OF COMMISSIONERS OF INLAND FISHERIES. 253 



cages were about 12 inches deep and 6 inches in diameter,* so that 

 the bottom containing the saucer was, in most cases, 7 or 8 inches 

 beneath the surface of the water. It is easy to perceive that the light 

 was able to enter the cages from all sides and from the top. 



Regarding the data presented in the tables, it should be borne in 

 mind that all the lobsters whose records are given in a single table 

 passed from the third to the fourth stage on the same night and were 

 subsequently subjected to the same conditions of food supply and to 

 the same degree of water temperature, both of which we know are 

 able to cause so great a difference in the duration of the stage- 

 periods when all other conditions are equal. 



*See Plate XL. 



