376 Unircrsitij of CnUfonila Publicalions in Zoology. [Vol- 4 



portionntely groater distance from the nucleus than they an_' in 

 colder waters. The contrast in length of horns of Ceratium from 

 tropical and arctic waters has been a matter of frequent comment 

 (see Chun '02) and the principle of the correlation of the pro- 

 cesses of pelaiiic or^^anisms with the function of flotation has often 

 been noted [see "Wesenberg-Lund ( :00) and Ostwald (:03j]. 

 Temperature thus bears a definite relation to the distance from 

 the nucleus to which the horns of Ccrfiliuni may exten^. In high 

 temperatures this distance is greater than at low ones. So also 



Mg. 25.- — ^ Ventral view of a normal Ceratium arcuatum. X 155. 

 Fig. 26. — ^Ventral view of another individual after distal autotomy of the 

 tips of the antapioals. X 160. 



in the fully grown organism it may follow that the distance in 

 the horn to which the normal processes of metabolism can be 

 maintained is in a similar manner afEected by. temperature. A 

 long-homed Ceratium entering a region of cooler water suffers, 

 it may be, a reduction in the radius of action of nuclear activity 

 and autotomy of a regulatory character follows. The sugges- 

 tion naturally arises that under conditions of lowered tempera- 

 ture a ferment is produced or becomes effective which brings 

 about a resolution of the wall and that the temperature regulates 



