150 SUMMARY OF CURRENT RESEARCHES RELATING TO 



obtained from the eggs, and may contain a lipase. Hence it is provi- 

 sionally called a lipolysin. 



" It seems probable that the factors tending to produce development 

 in the resting egg are of the nature of enzymes. The action of these, 

 Jobling found, may be inhibited by unsaturated fatty acids. The egg 

 remains in the resting stage so long as the action of these enzymes is 

 inhibited by the unsaturated fatty acid. The egg itself, when mature 

 and in a suitable medium, produces a lipolysin which binds this inhibitor. 

 The efficiency of the inhibitor may also be reduced by physical and 

 chemical means. In some groups, the spermatozoon appears to bind the 

 inhibitor, in others to increase the activity of the enzymes." J. A. T. 



Rhythmic Pulsation in Madreporic Vesicle of Young Ophiuroids. 

 — James F. Gemmill (Quart. Journ. Micr. Sci., 1919, 63, 537-40, 

 1 fig.). In young Ophiuroids, probably OpMoglypha alUda, at the stage 

 of a flattened disc with five blunt arms each with five tentacles, there 

 is a rhythmically pulsating madreporic thin-walled cavity entirely com- 

 parable to the madreporic vesicle of an Asterias larva. The pulsations 

 are extremely regular, occurring once in every eleven or twelve seconds. 

 It looks as if the essential part of the pulsation were the emptying and 

 filling of spongy tissue to one side of the vesicle. The author goes 

 on to discuss the axial organ (which he cannot regard as primarily a 

 genital stolon), and to compare the haemal systems of Enteropneusts 

 and Echinoderms. " J. A. T. 



Bottom Material Ingested by Holothurians. — W. J. Crozier 

 (Journ. Exper. ZooL, 1919, 26, 379-89, 2 charts). It has been found 

 possible to obtain a fairly accurate idea of the rate of feeding in 

 Stichopus mcehii Semper, and of the maximal contents of the gut in 

 individuals of different sizes. In certain typical areas 6 to 7 kilos 

 (dry weight) per square metre seem to pass through the intestine of 

 the Holothurians frequenting the spot. It is estimated that in the en- 

 closed "sink" of Harrington Sound the amount of bottom deposit annu- 

 ally eaten by Stichopus is perhaps 500 to 1000 tons. The fluid stomach 

 contents are sufficiently acid to dissolve some calcium carbonate. The* 

 mutual attraction of particles in the intestine is probably of small 

 significance for the formation of finely-divided particles. J. A. T. 



• 



Coelentera. 



Significance of Calyx in Alcyonacea. — Arvid R, Molander 

 (ArTciv Zoologi, 1918, 11, No. 22, 1-12). The term calyx has been used 

 loosely or ambiguously in reference to various types of Alcyonarians. 

 According to the author, it should mean (in Alcyonacea) the well- 

 defined basal region of the free or anthocodial portion of the polyp. 

 Into such a calyx the upper portion of the poljp can be usually re- 

 tracted, or it may also be that on the retraction of the upper portion into 

 the coenenchyma the calyx closes over it. The armature of the calyx 

 agrees in the main with that of the stolons, the basal membranes, or the 

 cortex of the colony. The spicules form eight longitudinal bands, and 

 are in the main longitudinally disposed. According to Molander there 



