ANATOMY AND PHYSIOLOGY OF CRl/SrACEA 127 



be located chiefly in the long antennae which serve, like a 

 blind man's cane, to inform the creature of what lies some 

 distance in front of him. The location of the chemical sense 

 seems to be in the smaller antennae. The eyes are well 

 developed and are placed on long stalks capable of a certain 

 degree of rotation and of retraction out of danger. The 



Fig. 128. — Upper figure, young lobster with otooyst in place showing 

 normal behavior. Lower figure, the same with otocyst removed ; keeps 

 upright with difiiculty. From Loeb. 



eye is compound like that of the cricket, and as many 

 partial images are formed on the sensitive part of the eye 

 — retina — as there are facets or elemental eyes (Fig. 127). 

 There seems to be no true sense of hearing in the lobster; 

 but it has a special organ of equilibrium and apparently a keen 

 sense of position. This organ is the otocyst and is located in 

 the basal joint of the smaller antennae. The young of the 

 lobster does not have an active otocyst (Fig. 128). The animal 

 tends to roll from side to side except as the hanging appendages 

 aid in keeping it stable. At a later stage its otoc5fst becomes 

 active, and then the larva keeps its appendages stretched out 

 in front and swims without rolHng over. The otocyst is the 

 chief organ that enables it to tell when it is right side up. 



