PROTOZOA, CCELENTERA, AND ECHINODEEMA 89 



great depth, are examined, it is impossible to say at 

 what points in its long journey from the bottom the 

 Protozoa it contains were caught. Even if dredges 

 and nets are used which can be closed by a messenger 

 at any particular depth, the problem cannot be very 

 easily settled ; for even if the protozoa shells that are 

 captured are found to contain a certain amount of 

 protoplasm, it must be proved that that protoplasm 

 is actually alive when brought on deck before we 

 know for certain that the species actually live on the 

 bottom, When the pelagic Foraminifera and Radio- 

 laria die and sink to the bottom, their protoplasm 

 probably disintegrates very slowly, and it is quite 

 probable that the floor of the ocean is littered with 



% 



the shells of truly pelagic protozoa, each containing a 

 greater or smaller amount of undeconiposed proto- 

 plasm. 



However, there is little doubt that there are 

 some truly abysmal Protozoa. Among the Radio- 

 laria, for example, it seems extremely probable 

 that the majority of the Phasodaria and many Spu- 

 mellaria live only in very deep water. ' A character 

 common to these abyssal forms,' says Haeckel, ' and 

 not found in those from the surface or slight depths, is 

 found in their small size and massive heavy skeletons, 



