294 FORESTRY [Bot. Absts. 



the same. From these data it is clear that the increase in rate of cure caused by sulphite and 

 bisulphite is due to the subsequent formation of sodium acetate. On the contrary, the de- 

 crease in the slope of the stress-strain curve (improvement) must be caused by the sulphur- 

 ous acid. Since both sodium acetate and sulphurous acid increase the tensile strength and 

 viscosity, sulphite and bisulphite must of course do likewise. — H . H . Bartlett. 



2015. De Vries, O. Invloed van verandering van tapvlak op latex en rubber. [Influ- 

 ence of the change of tapping surface on the latex and rubber.] Arch. Rubbercult. Neder- 

 landsch-Indie 3: 130-138. 1919. — In Hevea, the change of tapping system or the change of 

 tapping surface when accompanied by change of tapping system has great influence on com- 

 position of latex and properties of rubber. Opening a tapping cut on trees that have been 

 resting for some time, or opening a tapping cut on untapped trees gives a latex of high rub- 

 ber content and a rubber of very small rate of cure. However by merely changing to a new 

 tapping surface in bark that has had a period of rest while the whole tree with its coherent 

 system of latex vessels has not been at rest, no latex of especially high rubber content is 

 obtained, although latex from such a surface often shows phenomena ordinarily accom- 

 panying opening of a new cut; viz., tendency to oxidation (violet color), or yellow color of 

 latex— W. E. Cake. 



2016. De Vries, O. Latex en rubber van onder- en bovensnede. [Latex and rubber 

 from upper and lower cut.] Arch. Rubbercult. Nederlandsch. IndiS. 3: 124-129. 1919. — A 

 comparison of the properties of the latex and rubber from the upper and the lower cut when 

 tapping with two left cuts on one quarter. Data show that latex from each of two cuts is 

 nearly identical in all important characteristics. The greatest variation lies in the time of 

 cure where the product from the upper cut has a slightly shorter period. — W. E. Cake. 



2017. Dixon, H. H. Mahogany and the recognition of some of the different kinds by their 

 microscopic characters. Notes Bot. School Trinity Coll. Dublin 3:3-58. 23 pi. 1919. — 

 The structure of the wood of 45 species is described and each is illustrated by photomicro- 

 graphs. A key to these species based on microscopical characters is also given. — G. B. 



Rigg. 



2018. Etteu. Zusammenhange zwischen Bestandeslagerung und Schneedruck. [The 

 relation between locality of stand and snow damage.] Schweiz. Zeitschr. Forstwesen 70: 

 166-167. 1919. — During the months of March and April, 1919, there was heavy snow damage 

 noted in a stand of Scots pines 30 to 60 years old. This stand was on a slope to the south 

 and west of an older stand of timber. The snow in this locality usually comes from the 

 south and west and causes an exceptionally deep snow in the lee of this larger forest. ^V 

 young stand can not resist this heavy snow on account of its smaller stem and weaker root 

 system. This combination of conditions results in the heaviest snow damage that has been 

 noted. This condition extended over a region of about 30 acres. — J. V. Hofmann. 



2019. Feunow, B. E. [Rev. of: Zox, Raphael. Reconstruction and natural resources. 

 Jour. Political Econ. 27: 280-299. 1919.] Jour. Forestry 17: 59S-S00. 1919.— The regulation 

 of the national forests so as to provide homes for 300,000 families should be begun at the 

 present time, developing permanent yields wherever possible. Intensive development in 

 community settlement is needed at this time and is offered by real forestry.— J?. N. Mnnns. 



2020. Fluuy, P. H. Bodenverbesserungen oder Waldrodungen? [Soil improvement or 

 forest management?] Schweiz. Zeitschr. Forstwesen 70: 117-124. 1919. — The article dis :i sses 

 the possibilities of improving forest land through forest management and by artificial means 

 such as drainage and irrigation. The author states that 25 per cent of the forest land of 

 Switzerland is unproductive with possibilities of improvement. He advocates that the 

 soil can be greatly improved by proper management of different species; that swamps can be 

 made productive through drainage, and arid lands can be irrigated. In round numbers 

 there are possibly 140,000 hectares which are possible forest land. Work upon this basis 



