34 SUMMARY OF CUEEENT EESEARCHES EELATING TO 



of burl•o^vers the most efficient structure has probably been established 

 by natural selection, but ^Yith this interpretation the author Tvould 

 combine the idea that similar forces acting in a similar "uay have been 

 factors in causing similar modifications of structure in animals belonging 

 to widely different groups, just as tuberosities develop on bones at the 

 points of attachment of muscles of strenuous action. J. A. T. 



INVERTEBRATA.J ^ 



Mollusca. 

 * a. Cephalopoda. 



Luminescence ofWatasenia scintillans. — Rinnosuke Shoji {Amer^ 

 Joiirn. PliysioL, 1919, 47, 534-57). In this Japanese luminous squid 

 the luminescence is intracellular in three sets of structures. The lumi- 

 nescence is due to an oxidation. Alcohol, ether and chloroform inhibit 

 the luminescence in a few minutes, though in the first stage of the 

 process they excite the production of light to a certain degree. The 

 power of illumination is quickly recovered on the removal of the 

 narcotics. The most favourable temperature for luminescence is be- 

 tween 1G° and 81° C. ; direct sunlight has no influence on it ; the 

 effect of other environmental factors has been experimentally determined. 



J. A. T. 



<y. Gastropoda, 



Sensory Reactions of Chromodoris zebra. — W. J. Croziee and 

 L. B. Abey {Froc. Amer. Soc. Zool. in Anat. Record, 1919, 15, 34:5)^ 

 This Nudibranch reacts locally to tactile and chemical stimuli, to light 

 and shade, and perhaps to heat, through peripheral non-synaptic nerve 

 nets in the gill-plumes and perhaps other parts. It is positively photo- 

 tropic, probably through the eyes ; the branchial collar is also sensitive 

 to light ; the rhinophores are directive in relation to currents. 

 Chemotropic responses are important for conjugation. The positive 

 stereotropism of the anterior end of the foot is responsible for righting. 



J. A. T. 



Coloration of Chromodoris zebra. — W. J. Ceoziee {Proc. Amer, 

 Soc. Zool. in Anat. Record, 1919, 15, 349). The author's experiments 

 go to show that the coloration of this Nudibranch has no " warning " 

 significance, nor " concealing " advantage. It is not homochromic upon 

 natural backgrounds. The animal has an efficient repugnatorial defence,, 

 but its coloration is not adaptive. The incidence of various types of 

 injury (from the bites of fishes, etc.) is in no way correlated with the 

 kind, intensity, or distribution of the pigment. J. A. T. 



Arthropoda. 



Facial Suture of Trilobites. — H. H. Swinneeton {Geol. Mag.., 

 1919, 103-10, 2 figs.). It is argued that Trilobites form a compact 

 monophyletic group, the members of which at first underwent ecdysis 



