ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 311 



anal x (the brachianal of Bather, 1890) in the Crinoidea inadunata 

 and flexibilia. This conclusion is upheld in opposition to Austin H. 

 Clarke's suggestion that the anal plate of Antedon is homologous with the 

 radianal (Bather, 1890). J. A. T. 



Cell-division in Monaster and Narcotized Ova. — Theophilus S. 

 Painter (Journ. Exyer. ZooL, 1918, 24, 445-97, 5 pis., 10 figs.) has 

 studied the division of sea-urchin ova treated with narcotics, or shaken 

 so that many Monaster forms (with one division-centre) result. At each 

 division cycle, the egg-protoplasm is affected in three ways : (1) there 

 is a pronounced swelling of the ectoplasmic layer ; (2) this is followed 

 by intense changes in surface tension leading to the formation of 

 pseudopod-like processes ; (3) there is a flow of the superficial protoplasm 

 towards the area where the streaming is taking place. Ingenious 

 experiments point to the nucleus as the source of a second factor in cell- 

 division which finds expression in a swelling of the ectoplasm, great 

 changes in surface tension, and a flow of the cortical layers of protoplasm 

 towards the cleavage area. The asters seem to act as regulative centres 

 during cell-division ; by forming denser areas they restrict the action of 

 the nuclear factor to a prescribed area. J. A. T. 



Physiology of Synaptula hydriformis. — J. M. D. Olmsted {Journ. 

 Exper. ZooL, 1917, 24, 333-79, 2 figs.) has made a study of this 

 Holotliurian at Bermuda. It occurs in red and green varieties. It 

 feeds chiefly on a filamentous alga. There is a rhythmic pulsation of 

 the intestine. Nearly every specimen contained a mass of symbiotic 

 bacteria lying free in the body-cavity. There seems to be a well- 

 developed chemical sense. Probably, as in Lumhrkus (where, according 

 to Langdon, a specimen of 152 segments, 19 cm. long, has 150,000 

 sensory structures, about 1,000 to each segment), there are " universal 

 sense organs," receptive to tactile and photic as well as chemical stimuli. 

 This is at the other pole from man, where there are no recognizably 

 universal sense organs, but some twenty (Herrick) special senses. In any 

 case in Synaptula, in addition to eyes and otocysts, only one type of 

 sense organ has been found. J. A. T. 



Coelentera, 



Activities of Corymorpha. — G. H. Paeker {Journ, Exper. ZooL, 

 1917, 24, 303-31) has studied Corymorpha palma, a large and hardy 

 Hydrozoon. Its stalk measures as much as 10 cm. or more in length, 

 with a diameter at the thickest part of about 0*5 cm. The mucous 

 glands are insignificant ; cilia seem to be absent ; the stinging cells are 

 not under the control of the nervous system ; the muscles may or may 

 not be so controlled. There are four longitudinal ectodermic muscles — 

 of the stalk, of the proboscis, of the proximal, and of the distal tentacles. 

 There are two circular endodermic muscles — of the stalk and of the 

 proboscis. Both are stimulated directly, but the second is probably 

 also under partial nervous control. Nervous transmission is diffuse 

 except in the stalk, where it is predominantly longitudinal. The stalk, 

 proboscis, and tentacles show great autonomy. The locomotion is very 



