SURVEY OF INVERTEBRATES 99 



affin oil. The temperature was 18 to 22 ^C. The squids 

 ceased to respire in 40 to 60 minutes under these condi- 

 tions, and in 10 to 15 minutes when carbon dioxide was 

 dissolved in water. The shortened life in water contain- 

 ing larger quantities of carbon dioxide was not due, how- 

 ever, to a toxic action of this gas but to its influence in 

 hindering the oxygenation of the blood. Redfield and 

 Goodkind found that death by asphyxiation took place 

 at all those combinations of oxygen and carbon dioxide 

 pressures that prevented the arterial blood from absorb- 

 ing more than 0.5 to 1.5 volumes per cent of oxygen. 



The nervous system of cephalopods is quite sensitive 

 to the lack of oxygen. The ganglia generally succumb 

 earlier than the nerves, and the various ganglia are not 

 alike in their resistance to asphyxiation, according to the 

 investigations of Baglioni (1905) and Frohlich (1910). 



VI. ARTHROPODS 

 1. CRUSTACEANS 



Planktonic crustaceans are reported rather frequently 

 from surroundings poor in oxygen or completely devoid 

 of it; copepods especially, and to a lesser degree clado- 

 cerans, seem to tolerate well a reduced oxygen supply. 



Fresh water species have been observed in water quite 

 poor in oxygen by Birge and Juday (1908), Huss (1913), 

 Fehlmann (1917), Alsterberg (1922), Thienemann 

 (1925), and Lonnerblad and Naumann (1934). According 

 to Lauterborn (1916), Cycloids spp., Canthocamptus sp. 

 and Lathonoura rectirostris occur in oxygen-free sapro- 

 pelic habitats. Ziegelmayer (1923) found Cyclops albi- 

 dus in oxygen-free marshy waters, deep in mines, and 

 Cyclops serrulatus in sulfur springs of the Appenine 

 Mountains which were also devoid of oxygen (1924). 

 Ward (1940) encountered Cyclops aJhidus, as well as the 

 cladocerans Daphnia pulex and Sinwcephalus exspin- 

 osus, in the oxygen-free waters of a pond; Cyclops hi- 



