ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 149 



and later an aboral projection. The epidermis of this projection is 

 thrown into a number of involutions, by the unfolding of which it 

 somewhat suddenly increases in length at later stages, and assumes the 

 form of a peduncle, which fixes the animal by a mucous secretion. The 

 whole process, from the first division to the pedunculate fixed form, 

 occupied fourteen days. The peduncle consists externally of a prolifera- 

 tion of the epidermis of the body and internally of modified cells of the 

 coelomic epithelium, fatty particles and muscular elements. J. A. T. 



Rotatoria. 



Sex Determination in Hydatina. — A. Feanklin Shull {Joiirn, 

 Exper. Zool, 1918, 26, 521-44). "When water is saturated with an 

 atmosphere containing 60 p.c. of oxygen there is increased male- 

 production. The same is true, Shull and Ladoff have shown, with a 

 40 p.c. oxygen atmosphere. The lower concentration may, perhaps, be 

 a little more effective in inducing male-productien. Cultures in which 

 Euglena is used as food show increased male-production ; this is partly, 

 but not wholly, due to the oxygen liberated by the Euglena. But Euglena 

 as food is two or three times as effective as oxygen. Manure-scum used 

 as food is a male-repressing agent, J. A. T. 



Echinoderma. 



"Egg Secretion in Echinoderms. — Avalyn E. Woodwaed (Joiirn. 

 Exper. Zool., 1918, 26, 459-501, 2 charts, 3 figs.). In confirmation of 

 the work of Lillie and Glaser, it was found that the eggs of Asterias and 

 Arhacia secrete into the supernatant sea-water a substance which causes 

 the sperm of the same species to be activated, aggregated, reversibly 

 agglutinated, and paralysed. The secretion is also a parthenogenetic 

 agent. 



Further study showed that the presence of the secretion is necessary 

 for the fertilization of the Qgg, for (1) immature eggs, which cannot be 

 fertilized, produce a secretion with less than one-sixtieth the agglutina- 

 ting power of that produced by the same eggs when mature ; (2) eggs 

 from which the secretion has been washed do not develop when insemi- 

 nated, but if secretion be added before insemination they develop ; (3) 

 eggs of Arhacia which are " resistant " to fertilization late in the season 

 also produce little secretion, but fertilize normally if secretion is added. 



That the secretion has a dual nature is shown by the following 

 facts : — {a) it reacts with both the sperm and the ^^g ; {h) boiling destroys 

 its value as a parthenogenetic agent, but not as an agglutinin ; (c) peri- 

 visceral fluid of the same species inhibits autoparthenogenesis, but not 

 agglutination. 



The secretion is probably colloidal ; it contains carbon and nitrogen, 

 but gives no clear response to protein tests ; there is indication of the 

 presence of tyrosine, phenylalanine, or tryptophane. Two substances can 

 be precipitated from the same secretion — a sperm agglutinin and a par- 

 thenogenetic agent. The agglutinin resembles an enzyme in the effect 

 upon it of X-radiatiou. The parthenogenetic agent dissolves a fat 



