34 GENETICS [BoT. Absts., Vol. IX, 



213. WiTZGALL, L. Der Langenbrander Schirmkeilschlag von Forstmeister Dr. Eberhard 

 und der Wagnersche Blendersaumschlag in Gaildorf. [The Langenbrand shelterwood wedge 

 cutting and Wagner's selection strip cutting.] Forstwiss. Centralbl. 42: 431-436. 1920. — 

 A discussion and comparison of these 2 silvicultural methods, both of which aim to establish 

 the new stand by means of natural reproduction. — W. N. Spai-hawk. 



214. ZwiLLiNG, C. La conversion des taillis sous futaie du departement de la Moselle 

 en haute futaie. [Conversion of coppice under standards into high forest in the department of 

 Moselle.] Rev. Eaux et Forets 59: 33-39. 1921.— In 1830 the French forest administration 

 began the conversion into high forest of a part of the 32,600 hectares of broadleaf national 

 forests in the department of Moselle. These had previously been managed as coppice under 

 standards, as are most of the communal and private forests today. The rotation of the cop- 

 pice was reduced from 25 or 35 to 20 years and the number of reserves was gradually increased 

 during successive cuttings so as to form a selection high forest. The work was continued by 

 the Germans after the annexation of Alsace-Lorraine, but in 1882, as a result of decreased 

 prices for fuel wood, they made the mistake of undertaking the conversion of all the national 

 forests. This resulted in failure on the thin, clayey soils not suited to the production of broad- 

 leaf high forests. Another later mistake, which was, however, soon rectified, was the applica- 

 tion of a rigid diameter limit, sometimes with disastrous results. Aside from this the forests 

 under conversion were in general well cared for. Thinnings as well as reproduction cuttings 

 were used in effecting the conversion and were carried out in the lower as well as the upper 

 story. Double high forests were often established in which the rotation of the upper story, 

 usually oak, was twice that of the lower story, usually beech, with both of which natural 

 regeneration was comparatively easy. The execution of the various cuttings was greatly 

 facilitated by the fact that under the German administration the logging was done by the 

 government, which, because of its direct interest in the results, was able to handle the work 

 more effectively than private operators. — S. T. Dana. 



GENETICS 



George H. Shull, Editor 

 James P. Kelly, Assistant Editor 



(See also in this issue Entries 2, 6, 7, 12, 18, 29, 30, 47, 48, 52, 62, 92, 94, 164, 286, 305, 316, 



319, 331, 338, 339, 342, 382, 402, 452, 453) 



215. Anonymous. [Rev. of: Babcock, E. B., and R. E. Clausen. Genetics in rela- 

 tion to agriculture. 15 X 23 cm., xx -f- 675 p., 4 colored pi., 239 fig. McGraw-Hill Book Co.: 

 New York, 1918 (see Bot. Absts. 1, Entry 210, 220, 244; 2, Entry 233; 3, Entry 446).] Sci. 

 Prog. [London] 14: 169-171. 1919. 



210. Anonymous. Heredity and social fitness. [Rev. of: Key, Wilhelmine E. 

 Heredity and social fitness; a study of differential mating in a Pennsylvania family. Carnegie 

 Inst. Washington Publ. 29fi. 102 p., 2 folded diagrams. 1920 (see Bot. Absts. 9, Entry 239).{ 

 Nature 106: 360-361. 1920. 



217. Arey, Leslie B. On monozygotic human twins. [Abstract.] Anat. Rec. 21: 44. 

 1921. — Two specimens of early monozygotic human twins, each case unique of its kind, are 

 presented. The first comprises 2 embryos, each 12.3 mm. long, contained within a single 

 amnion and chorion; except for some shrinkage of the entire specimen, the embryos are nor- 

 mal. Each possesses its own umbilical cord and yolk-stalk; the latter are inserted separately 

 on a common yolk-sac. This furnishes for the first time direct proof of the origin of human 

 identical twins from a single ovum. The second specimen is of normal monochorionic twin 

 embryos, each lying within its own amnion. One member of the pair (11.5 mm. in length) 

 has a normal yolk-stalk and sac (4.5 X 6 mm.); the other individual (12 mm. long) lacks these 

 structures completely, as gross and microscopic examination prove. Certain inferences are 



