22 SUMMARY OF CURRENT RESEARCHES RELATING TO 



so far available does not enable one bo ascribe any certain origin to the 

 violet pigment, nor to account for its development in such different 

 organisms as Murex, Par punt. Bonellia, and Diazona. 



Tunicates of Santander.* — E. Rodriguez y Lopez Neyra de Gorgot 

 gives a short account of Tunicates collected at the Murine Biological 

 Station of Santander. The collection includes four species of Sulpa. 

 two of Molgula, four of Ascidia, two of L&ptoclinum, and so on. A 

 diagnostic key is given, and some illustrations of the branchial apparatus 

 of Ascidians and of the spicules of some compound forms. 



Circulation and Luminescence in Pyrosoma.t — Fritz Burghause 

 describes the heart and circulation in the ascidiozooid of Pyrosoma 

 giganteum, and refers more briefly to the cyathozooid. He deals with 

 the various blood-sinuses ; the course of the circulation, as compared with 

 that of Ascidians and Salps ; the importance of tbe food-carrying function ; 

 the periodic reversal of the heart ; the influence on the heart's activity 

 of stimuli affecting the surface of the body ; the influence of lack of 

 oxygen ; the influence of products of metabolism : the influence of altera- 

 tions of temperature ; the changes that occur during the moribund 

 period. The luminescence is not due to the direct oxidation of a 

 luminous substance ; it has its seat in the luminous organs, the ovary, 

 and the embryo in the cloaca ; the colour observed was always greenish- 

 blue ; the luminescence of other animals serves to exite that of Pyrosoma ; 

 direct sunlight is prejudicial. Experiments showed that the luminescence 

 had no protective value as far as fishes and crabs were concerned. 



INVERTEBRATA. 

 Mollusca. 

 7- Gasteropoda. 



Apparent Absence of Sexual Characters in Shell of Neritina 

 fluviatilis.} — A. E. Boycott and J. W. Jackson have examined nearly 

 300 shells of this fresh-water Gasteropod to see whether the sexes 

 differed in size, shape, texture, colour, or other external features. They 

 were not able to find any sexual characteristic. The examination of 

 about forty radulas showed no sexual difference. 



5. Iiamellibranchiata. 



Luminous Organs and Nervous System of Pholas dactylus.§ 

 J. Forster describes five luminous organs in this bivalve — two narrow 

 parallel stripes on the septum in the branchial siphon, two irregular 

 spots in the mantle, and a horseshoe-shaped organ on the posterior 



* Mem. R. Soc. Espaiiola Hist. Nat., ix. (1914) pp. 489-512 (10 figs.). 



+ Zeitschr. wiss. ZooL, cviii. (1914) pp. 430-97 (2 pis., 5 figs., and 9 tables). 



J Ann. Nat. Hist., xiv. (1914) pp. 369-75 (2 figs.). 



§ Zeitschr. wiss. ZooL, cix. (1914) pp. 349-92 (1 pi. and 15 figs.). 



