210 GENETICS [Bot. Absts., Vol. V, 



1589. Mttnns, E. N. Effect of fertilization on the seed of Jeffrey Pine. Plant World 22: 

 138-144. 1919. — Author reports on results of various cross- and self- pollinations among 8 

 trees of Pinus Jeffreyi, three of which were thrifty, two mistletoe-infected, one insect infected, 

 and two "suppressed trees." On basis of observations author recommends that seed should 

 be collected from localities with strong winds at time of flowering so that cross-pollinated 

 seeds may be secured; and that for heavy seeds and consequent stronger seedlings collections 

 should be from thrifty parents ; poor trees gave largest number of seeds to pound but produced 

 smallest nursery trees ; and that in timber-sale practice only thrifty trees should be left. [See 

 also Bot. Absts. 5, Entry 1375.] — James P. Kelly. 



1590. Myers, C. H. The use of a selection coefficient. Jour. Amer. Soc. Agron. 12: 



,™> nr> , mn Number of ripe ears , „, . , , 



106-112. 1920. — - - ; — = percentage of maturity. Ihe average yield per 



Total number of ears 



stalk of maize was determined in pounds. It was desirable to combine the yield and the maturity 



into a single expression which would serve as a basis for selection. The average yield per 



stalk times the percentage of maturity gives the ''selection coefficient."— F. M. Schertz. 



1591. Nachtsheim, Hans. Crossing-over-Theorie oder Reduplikationshypothese? [The 

 crossover theory or the reduplication hypothesis?] Zeitschr. indukt. Abstamm. Vererb. 22: 

 127-141. 4 fig. Jan., 1920. 



1592. Nachtsheim, Hans. Zytologische und experimentelle Untersuchungen iiber die 

 Geschlechtsbestimmung bei Dinophilus apatris Korsch. [Cytological and experimental studies 

 on the sex determination of Dinophilus apatris Korsch.] Arch. Mikrosk. Anat. 93: 17-140. 

 4 pi., 5 fig. Nov., 1919. 



1593. Naef, A. Idealistische Morphologie und Phylogenetik. (Zur Methodik der sys- 

 tematischen Morphologie.) [Idealistic morphology and phylogeny. (On the method of system- 

 atic morphology.) ] 77 p., 4 fig- Jena, 1919. 



1594. Noack, Konrad. [German rev. of: Stomps, Theo. J. Gigas -mutation mit und 

 ohne Verdoppelung der Chromosomenzahl. [Gigas-mutation with and without doubling of 

 the chromosome number. Zeitschr. indukt. Abstamm. Vererb. 21: 65-90. 3 pi., 4 fig- July, 

 1919. (See Bot, Absts. 4, Entry 778.) ] Zeitschr. Bot. 12: 36-39. 1920. 



1595. Noyes, Hilda H. The development of useful citizenship. Jour. Heredity 11: 88- 

 91. Feb., 1920. 



1596. Nuttall, G. H. F. The biology of Pediculus humanus. Parasitology 2 : 201-220. 

 1 pi., 1 fig. 1919. — Lice reared on white backgrounds developed very little pigment and ap- 

 peared whitish or translucent but those reared on black backgrounds became very darkly 

 pigmented thus showing that pigmentation is not inherited. In some lots taken from their 

 host as high as 9 per cent of the adult individuals were hermaphrodites. — D. D. Whitney. 



1597. O., A. Zonal Pelargoniums. Gard. Chron. 66: 157. Sept. 20, 1919.— Maxime Kav- 

 olsky, a comparatively new variety is briefly described. — A. C. Hildreth. 



1598. Palmgren. Rolf. Till Kannedomen om Abnormiteters Nedarfning hos en del 

 Husdjur. [Inheritance of abnormalities in certain domestic animals.] Acta Soc. pro fauna 

 et flora fennica 44: 1-22. 1918.— See Bot. Absts. 5, Entry 1548. 



1599. Palmgren, Rolf. Tvenne bastarder mellan getbock och fartacka, fodda i Hog- 

 holmes zoologiska tradgard. [Two hybrids between sheep and goats produced in Hogholm zoolo- 

 gical gardens.] Med. pro fauna et flora fennica 44: 124-125. 1918.— See Bot. Absts. 5, 

 Entry 1548. 



1600. Pammel, L. H., and C. M. King. An annual white sweet clover. Proc. Iowa Acad. 

 Sci. 25: 249-251. PI. 4-6. 1920.— See Bot. Absts. 5, Entry 1191. 



