346 JOHN F. FULTON, JR 



vibrate much less regularly. The latter, inasmuch as they are 

 motile, have in all probability been torn from the cihated 

 lining of the gastrovascular cavity ; with acetic acid or neutral 

 red their cilia may very easily be demonstrated. 



The coloration of Condylactis, it should be emphasized, is 

 due largely, but not entirely, to this yellow flagellate. The 

 tissue of the tentacles is itself colourless (Rand, 1909 ; Parker, 

 1917), as is shown when a tentacle is transected. The brownish- 

 yellow colour, which is a constant feature of the uninjured 

 tentacle, is therefore due to the presence of the flagellate organ- 

 ism in the internal fluid. This may readily be shown by 

 examining the liquid contents of the tentacle. When an 

 animal is withdrawn from the aquarium with the tentacles in 

 expanded condition the internal pressure on the gastrovascular 

 fluid causes minute streams of water to issue from the terminal 

 pore of each tentacle. If some of the fluid so exuded be caught 

 in a watch-glass it occasionally contains the ' symbiotic " 

 organisms ; under normal conditions of exudation, however, 

 they probal)ly do not escape when the tentacle contracts. 



Not only are the tentacles coloured by the presence of 

 Zooxanthellae, but the column itself owes much of its colour 

 to this organism. However, the column also possesses large 

 collections of red pigment granules, some patches being as 

 much as 2 mm. in diameter. These are more highly con- 

 centrated in the lower parts of the column than in the upper, 

 which gives to the l)asal region an intense red colour, while 

 the upper parts tend toward the brownish yellow of the 

 tentacles. 



In two Siphonophora, Velella spirans and Por- 

 pita umbella, Kuskop (1921) has found Zooxanthellae in 

 abundance ; they reside chiefly in the ' hepatic canals ", 

 so called, and in the gonophores. Their occurrence in the latter 

 organs strongly suggests that the association of the Zooxan- 

 thellae with these coelenterates is continuous from one genera- 

 tion to another. Before discussing the significance of these 

 observations the condition of the pigment in Actinia ber- 

 mudensis will also be described. 



