1916 



Shelfordj on Physiological Differences 



165 



Table 3. Shoxving the relative resistance of crabs from different depths 



to high temperature. Compare depth at which taken and 



from "which commonly recorded with survival time 



♦Occurs above low tide. 



**Red, from red algae; Station C. 



B. Relations to Fresh Water 



Fresh water experiments were conducted in small dishes surrounded 

 by running sea water which kept the temperature the same as sea water 

 used as controls. In the case of the animals ))ut into the fresh water 

 the results were often very striking. Such animals as shrimps, which 

 stand in an u])right jiosition, fall over in from 2 to 15 seconds after being 

 ])]aecd in the fresli water and do not move extensively afterward. Move- 

 ment may be induced, for a coiisider/ible jxriod. by pinching the abdomen, 

 but finally the movement of the gill bailer is all tlint can be detected. 



