248 GENETICS [Bot. Absts., Vol. VI, 



1691. Herlant, Maurice. L'acide carbonique comme agent de parthenogenese experi- 

 mentale chez l'oursin (Paracentrotus). [Carbonic acid as an agent of experimental partheno- 

 genesis in the sea-urchin (Paracentrotus).] Compt. Rend. Soc. Biol. 83: 188-190. 1920. 



1692. Hertwig, Gunther. Das Schicksal des vaterlichen Chromatins im Kreuzungs- 

 experiment. [The fate of paternal chromatin in the crossing experiment.] Arch. Mikrosk. 

 Anat. 94: 28S-302. 1 fig. July 15, 1920. 



1693. Hertwig, Oscar. Allgemeine Biologie. [General biology.] 5th ed., improved and 

 enlarged, 8vo., xvi + 800 p. Gustav Fischer: Jena, 1920. 



1694. Hertwig, Paula. Abweichende Form der Parthenogenese bei einer Mutation von 

 Rhabditis pellio. Eine experimentell cytologische Untersuchung. [Aberrant form of partheno- 

 genesis in a mutation of Rhabditis pellio. An experimental cytological study.] Arch. Mikros. 

 Anat. 94:303-337. 1920. 



1695. Hertwig, Paula. Haploide und diploide parthenogenese. [Haploid and diploid 

 parthenogenesis.] Biol. Zentralbl. 40: 145-174. April-May, 1920. — Summary of known facts 

 concerning maturation and development in artificial and physiological parthenogenesis. 

 Stimuli to artificial parthenogenesis are classed as chemical, physical, and biological. Time 

 at which stimulation acts determines, in different material, whether development starts with 

 diploid or haploid number of chromosomes. As a rule number is haploid. Later, from nat- 

 ural or artificial causes, it may become diploid. Specific examples are given, and literature 

 is cited. Development of artificially parthenogenetic eggs is mostly of short duration. 

 Author points out that complete development in presence of only haploid number of chromo- 

 somes has so far proven impossible. Defect is hardly in mere number of chromosomes, but 

 perhaps in interrelation of nucleus, protoplasm, and yolk. It is questionable whether nor- 

 mal development can occur even in physiological parthenogenesis in presence of haploid 

 number of chromosomes. Evidence at hand does not prove that it can. — Cases are mentioned 

 in which natural parthenogenesis occurs in animals in absence of reduction, and comparable 

 phenonena in plants are described. In no case in plants has development occurred with 

 haploid nuclei in a generation normally diploid. In animals of Hymenopteran type, egg 

 undergoes normal reduction whether it later develops parthenogenetically or is fertilized, 

 and sex depends on presence or absence of fertilization. In some of those developing parthe- 

 nogenetically with haploid nuclei, number of chromosomes is later doubled, at least in somatic 

 cells. Cytology of honey bee is critically considered in this connection. — A. Franklin Shull. 



1696. Hoche, Leon, and Rene Morlot. Evolution parthenogenetique de l'ovule dans 

 l'atrophie de follicule a l'etat de maturite. [Parthenogenetic development of the egg to maturity 

 in a case of atrophy of the follicle.] Compt. Rend. Soc. Biol. 83: 1152-1154. July, 1920. 



1697. Hromadko, J. Variabilitat der Nachkommenschaft derselben Futterriibenmutter 

 in der 1. Generation. [The variability of progenies of the same mother beet in the first genera- 

 tion.] Zeitschr. Zuckerindus. Bohmen 42: 581-601. 1918. 



1698. Jollos, Victor. Experimentelle Vererbungsstudien in Infusorien. [Experimen- 

 tal studies of heredity in Infusoria.] Zeitschr. indukt. Abstamm. Vererb. 24: 77-79. Aug., 

 1920. 



1699. Jones, D. F. Selective ferti'ization in pollen mixtures. Biol. Bull. 38:251-289. 

 May, 1920. — By the use of the ingenious system of reciprocal crosses the author shows 

 decisively that in Zea mays self-fertilization, although detrimental to the development of the 

 progeny, is favored at the expense of cross-fertilization. Using the increase in the percentage 

 of the cross-pollinated seeds as an indication of the germinal differences between the parents, 

 the author calculated the correlation coefficient between the percentage of increase and the 

 percentage of deviation in favor of self-fertilization, and found it to be 0.496 ± 0.093. He 

 concluded from this coefficient that, "In proportion as the cross-fertilization benefits the 



