48 GENETICS [BoT. Absts., Vol. VIII, 



308. Okkelberg, Peter. The early history of the germ cells in the brook lamprey, Ento- 

 sphenus wilderi (Gabe), up to and including the period of sex differentiation. [Abstract.] 

 Anat. Rec. 20:201. 1921. — The germ cells are segregated before the germ layers are defi- 

 nitely established. They are first recognized about the time when the mesoderm separates 

 from the entoderm (embryo about 191 hours old). The definite germ cells, in both sexes, 

 take their origin from these primordial germ cells, and from no other source. Numerous germ 

 cells degenerate in every individual and they never take part in the formation of somatic 

 structures. During the period of sex differentiation 2 types of cells are found in practically 

 every individual, those which continue to divide and those which stop dividing and enter 

 upon a synaptic and growth phase. The former are taken to be potential male cells (sper- 

 matogonia) or indifferent cells and the latter potential female cells (primary oocytes). 

 The relative proportion of the 2 kinds of cells apparently determines whether the larva shall 

 become a male or a female. Observations seem to warrant the conclusion that each larva 

 carries in it the potentiality of both sexes and that sex, therefore, is not irrevocably fixed at 

 or before fertilization. When a larva becomes definitely established as a male there rudi- 

 mentary eggs are frequently found in the adult testis. In the adult condition the number of 

 individuals of each sex is about the same. — Peter Okkelberg. 



309. Orensteen, Myer M. Correlation of cephalic measurements in Egyptian born 

 natives. Biometrika 13 : 17-24. 1920. — Means, standard deviations, and coefficients of corre- 

 lation of length and breadth of head are given for different provinces. Correlation ranges 

 from + 0.208 ± 0.033 to + 0.369 ± 0.028— John Rice Miner. 



310. Osi.ER, H. S. Origin and development of pedigreed varieties of grains. Michigan 

 Acad. Sci. Ann. Rept. 21: 139-143. 1919. — Important varieties of small grains came into use 

 largely in three ways, introduction, selection, and hybridization. The origin of a number of 

 improved varieties is given. The method of production and the distribution of Red Rock 

 wheat and Rosen rye is briefly summarized. — H. K. Hayes. 



311. Pelseneee, Paul. L'hybridation chez les MoUusques. [Hybridization in mol- 

 luscs.] Compt. Rend. Acad. Sci. Paris 168: 1056-1059. 1919. 



312. Pf:zARD, A. Loi du "tout ou rien" ou de Constance fonctionnelle, relative k Paction 

 du testicule consldere comme glande endocrine. [Law of "all or nothing" or of functional 

 constancy relative to the action of the testis considered as an endocrine gland.] Compt. Rend. 

 Acad. Sci. Paris 172: 89-92. 1921. 



313. PfizARD, A. Secondary sexual characteristics and endocrinology. Endocrinology 4: 

 527-540. S fig. 1920. — A number of secondary sexual characters are dependent upon internal 

 secretion of testis. Effect of secretion begins at puberty and continues, in poultry, through 

 sexual life with remarkable constancy. Effect is lost with removal of testis, but not more 

 than jiV of total weight of testis is required to produce effect. Any fraction of testis large 

 enough to produce any morphogenetic effect produces the entire effect (tested on combs). 

 Some characters recognized as racial are dependent on this secretion. Meat diet produces 

 modification in structure and sexual behavior, not directly, but by first inducing changes in 

 testis. — A. Franklin Shull. 



314. Plahn-Appiani. Die Individualitat von Zucker- und Futterriibe. [Individuality of 

 sugar beets and fodder beets.] Centralbl. Zuckerindust. 27 : 220-221. 1919. — Author refers to 

 doubt sometimes e.xpressed about distinguishing certain white fodder beets from sugar beets. 

 He would not ascertain sugar content as this is transgressive in its variation but would use a 

 criterion dependent on structural characteristics as specific weight or data on volume secured 

 in calculation of specific weight. The volume figures for sugar beet lie between 92 and 95 

 and for fodder beets from 97 to over 100. — James P. Kelly. 



