30 G SUMMARY OF CURRENT RESEARCHES RELATING TO 



It is probably respiratory. The locomotion is accomplished by a wave- 

 like movement which progresses over the pedal disk in the direction 

 of locomotion. Each point on the disk is successively raised from the 

 substratum, moved forward, and put down. The attachment of Condy- 

 Jactis, Sagartia, and other forms studied, is due chiefly to adhesion 

 heightened by the secretion of a thick slime rather than to a sucker-like 

 action of the pedal disk. 



The locomotion is due to the circular muscle of the pedal disk, the 

 basilar muscles, and the longitudinal muscles of the mesenteries, all of 

 which act on the fluid-filled spaces in the pedal region of the animaL 

 The pressure thus generated is not above that of 6 c.cm. of water. 

 Creeping can be effected by an Actinian from which the oral disk has 

 been cut away. It follows that the pedal portion of the anemone, like 

 its tentacles, must have a neuro-muscular equipment sufficient for its own 

 activity. 



In a specimen of Sagartia with a pedal disk about 4 mm. in diameter 

 the locomotor wave coursed over the disk in an average time of 



I • 65 minutes. With each wave the animal progressed on the average 

 1"2 mm. In a specimen of Condylactis with a pedal disk 130 by 

 80 mm,, the passage of a locomotor wave required on the average three 

 minutes, and the animal progressed for each wave on the average 



II •4 mm. 



Heliotropism in Eudendrium.* — Jacques Loeb and Hardolph 

 Wasteneys have re-investigated the behaviour of the hydroid Eudendrium, 

 which is positively heliotropic, to test afresh how it conforms to the 

 Bunsen-Roscoe law whereby the heliotropic effect is determined by the 

 product of the intensity into the duration of iUumination. Experiments 

 carried on by a somewhat different method from those previously 

 published by Loeb and Ewald harmonize with the idea that the Bunsen- 

 Eoscoe law is the correct expression of the influence of light on the 

 heliotropic reactions of the hydroid. 



Porifera. 



Animals Associated with a Sponge.f — Ch. J. Gravier describes 

 an interesting association. A Hexactinellid sponge described by Topsent 

 as Sarostegia oculata, with many branches spreading in a fan-like 

 fashion, was found to be covered by small Actinians, the largest 4 mm. 

 in diameter. The Actinians have two circles of endacmian tentacles, 

 about thirty in number ; the mesenteries have weak musculature ; 

 there are no acontia or cinclidse ; the outer surface is rigid with a 

 coating of Foraminifera. On dead branches there were no Actinians. 

 It seems therefore that they utilize the currents produced by the sponge. 

 Inside the sponge in branching galleries there lives a species of 

 Hermadion in the polychget family Polynoidse, which may perhaps 

 secure the absence of more objectionable creatures. 



* Journ. Exper. Zcol., xii. (1917) pp. 187-92. 

 t Comptes RenduB, clxiv. (1917) pp. 333-6. 



