98 GENETICS [Bot. Absts., Vol. IV, 



and anesthetics prevent cytasters. Agents alter permeability of egg membrane. Cytasters 

 are produced artificially only during period of permeability of egg membrane. Author sug- 

 gests salts penetrate egg at this time, become irregularly distributed in egg, and "salted" 

 spots become centers of coagulation and liquefaction of colloids, thus forming asters. — A. 

 Franklin Shull. 



606. Herlant Maurice. Comment agit la solution hypertonique dans la parthenogenese 

 experimentale (Methode de Loeb). II. Le mecanisme de la segmentation. [How the hyper- 

 tonic solution acts in experimental parthenogenesis (Method of Loeb). II. The mechanism of 

 segmentation.] Arch. Zool. Exp. et G6n. 58: 291-314. PL 13-14- July, 1919— Egg of Para- 

 centrottts lividus stimulated to development by butyric acid alone forms monaster or several 

 monasters one after another at successively shorter intervals and of successively shorter dur- 

 ation, but egg does not divide. Nucleus disappears while monasters are present but reappears, 

 each time of larger volume, after each monaster, and toward end of series of monasters it may 

 be fragmented. Fixed material shows that chromosome number, normally 18, doubles each 

 time monaster is formed, but no cell division occurs and all chromosomes are recombined into 

 one nucleus of larger size. Frequently at time of third or fourth monaster small spindle, per- 

 haps in nucleus, is formed with very large number of chromosomes on its equator, in which 

 condition egg remains until it disintegrates. In eggs treated first with butyric acid, then re- 

 turned to sea water, and finally for 30 minutes to hypertonic solution, accessory asters are 

 formed in addition to aster near nucleus. If only one accessory is formed it approaches the 

 perinuclear aster, spindle is formed, and egg divides. Presence of two or more accessory as- 

 ters may result in irregular divisions. Aster is physiological, not morphological phenomenon. 

 Review of literature indicates most features of mitosis are largely independent of each other, 

 and none is indispensable. — A. Franklin Shull. 



607. Hertwig, Paula. Keimesschadigung durch Physikalische und chemische Ein- 

 griffe. [Injury of the germ cells by physical and chemical means.] Zeitschr. indukt. Abstamm. 

 Vererb. 19: 79-99. Mar., 1918. — Author gives a short review of the most important recent 

 contributions to the study of injurious effects of physical and chemical factors on develop- 

 ment of germ cells. — She discusses briefly experiments of O. Bury (1912) on eggs of Echinids 

 with low temperature; those of O. Hertwig (1913) on spermatozoa of Rana fusca and Rana 

 esculenta with solutions of different chemical substances (methylenblue, eosin, fuchsin, atoxyl, 

 sublimate, chloralhydrate, etc.) ; those of G. and P. Hertwig (1913) on germ cells of am- 

 phibia and fishes with different chemical substances (chloralhydrate, strychnine, nicotine, 

 methylgreen, etc.); those of C. Herbst (1907 and 1913) on spermatozoa with radium solu- 

 tions; those of O. Warburg (1910) with ammonia and thymol solutions; those of Mairet 

 and Cambebmal (1&S8) with alcohol; and those of Nice (1912) with alcohol, nicotine, tobacco 

 smoke and caffeine. The general results of these experiments are stated in a few words. — 

 The greater part of the article is devoted to a special consideration of the experiments by 

 Stockard (1910, '12, '14), Stockard and Craig (1912), and Stockard and Papanicolaou 

 (1916) on the action of alcohol on the germ cells of mammals. She considers these experiments 

 to show conclusively the modification of the germ cells in mammals by chemical stimuli, but 

 doubts whether the differences in results from treated males and females will continue to be 

 significant after greater numbers are studied. — The article is as a whole a fair review of the 

 papers considered. — George N. Papanicolaou. 



608. Hessing, J. Mitteilungen beziiglich der Variabilitat einiger Grasarten. [Communi- 

 cations concerning the variability of some grass species.] Zeitschr. Pflanzenziicht. 7: 53-57. 

 Juno, 1919. — Marked variability in characters of Lolium italicum and L. perennc. Selfing 

 three years isolated 3 groups, tall V-form, bushy U-form and low spreading plants each of 

 which bred nearly true. Data arc given on breadth and length of leaf and spike density. 

 Author holds that selfing and individual-plant study is correct method of breeding these 



es. — R. J. Garber. 



