ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 281 



repeat the size and symmetry of the plates found at the corresponding 

 place in the normal arm. The lost pyloric caeca are not regenerated ; a 

 cicatrization occurs. The inter-radial space is much reduced ; the 

 Polian vesicle is absent ; the gonads are reduced in number. J. A. T. 



Hermaphroditism in Viviparous Ophiuroids. — Th. Moetensen 

 {Acta Zoologua, 1920, 1, 1-18, 1 pi.). No fewer than sixteen 

 out of the twenty species known to be viviparous are hermaphrodite. 

 As hermaphroditism is otherwise unknown among non-viviparous 

 Ophiuroids there must be some direct relation. In Ophiacantha vivipara, 

 OphiomitreUa clavigera and Amphiura horealis the hermaphroditism is 

 protandrous. In Ophiomyxa vivipara, Ophiacajitha imago and Ophio- 

 tjalfa vivipara the sexes are separate. Self-fertilization appears to be 

 possible in most of the hermaphrodites. It is striking that of the three 

 viviparous species of Ophiacantha, one has separate sexes, another is a 

 protandrous hermaphrodite, and a third is a true hermaphrodite. The 

 problem is left unsolved. J. A. T. 



Ccelentera. 



Movements and Luminescence in Renilla. — ^G. H.Parker {Journ. 

 Exper. Zool., 1920, 31, 475-515, 1 pi, 12 figs.) Renilla shows two 

 forms of peristalsis : peduncular, with waves running distally over the 

 peduncle ; and rachidial, with waves running in the opposite direction 

 over both peduncle and rachis. Peduncular peristalsis is primarily 

 concerned with sinking the peduncle into the sand and thus anchoring 

 the animal. It is also the means of bringing about a complete with- 

 drawal of the animal under the sand and of a certain amount of locomo- 

 tion. It is secondarily concerned with the distribution of fluid within 

 the animal during distention. Eachidial peristalsis raises Renilla out 

 of the sand and distributes the fluids contained within its body. It is 

 not concerned with effective locomotion. In tlie activities of Renilla 

 the zooid as a unit is dominated by the colony. 



Renilla is naturally highly phosphorescent at night but not by day. 

 At night the phosphorescence can be reduced by exposing it to light, 

 and by day the phosphorescence can be developed by putting the animal 

 in the dark. Renilla is excited to phosphorescence only by stimulation, 

 particularly by mechanical or electrical stimuli. Concentric waves 

 emanate from the spot stimulated. The impulses are temporarily 

 interrupted by magnesium sulphate. Phosphorescence is limited to the 

 upper surface of the rachis, and is produced by masses of whitish 

 material that surround the siphonozooids and the bases of the autozooids. 

 Peristalsis consists of muscular waves whose rhythm is probably 

 myogenic in origin. Phosphorescence, the withdrawal of autozooids, 

 and general contractions are called forth by impulses, often wave-like 

 in character, and probably neurogenic in origin. J. A. T. 



Ciliary Movements in Beroe. — G. F. Gothlik^ {Journ. Exper. 

 Zool., 1920, 31, 103-41). In Beroe cucumis there occur conditions 

 when all the swimming plates are inhibited in their movements, beat 

 more slowdy, or remain stationary in a position of rest, without any 

 muscular retraction of the meridian rows. These conditions of primary 



