248 BOTAMCAL GAZETTE [September 



He found high salt supply gives vegetative growth, while low salt supply 

 induces fruiting. Fischer found that increasing photosynthesis and the 

 supply of carbohydrate material, through increased C0 2 pressure, the nitrogen 

 supply remaining constant, induces the reproductive phase. Finally, in a 

 series of very critical experiments and analyses, Kraus and Kraybill found 

 that a relative abundance of carbohydrate over nitrogenous material in the 

 plant induces fruitfulness, while a relatively greater nitrogen supply induces 

 vegetative growth. Excessive carbohydrate over nitrogen inhibited both 

 vegetative and reproductive growth. All of this work shows a very close 

 relation between the conditions of nutrition in the plant and the type of growth 

 expression. Garner and Allard have undoubtedly made a contribution 

 of great value to the subject of vegetation and reproduction in plants. The 

 reviewer feels, however, that their conclusions are much broader than a care- 

 ful review of the whole subject warrants. It would be difficult, for example, 

 to explain the phenomenon of alternate fruiting in many of our orchards on 

 the basis of length of day influence. A critical study of the nitrogen and 

 carbohydrate metabolism under these reduced exposures to illumination would 

 be of great value in arriving at an understanding of the many factors in plant 

 growth and reproduction. — J. R. Magxess. 



Ecological research. — In a report of research in progress under the direc- 

 tion of the Carnegie Institution, Director MacDougal 11 reports progress 

 upon a number of interesting problems. Shreve has continued investigations 

 upon the vegetation of the arid Avra Valley, and reports progress in a soil 

 temperature survey of the United States and Canada. Cannon presents 

 some conclusions derived from a field study of the vegetation of central, 

 northern, and southwestern South Australia, as well as some further results 

 in the investigations of the reactions of roots to varying amounts of carbon 

 dioxide in the soil. He has also some data as to the size and form of leaves 

 of desert plants. Cooper reports the beginnings of a study of the strand 

 vegetation of the Pacific Coast at Coronado and Monterey, California. These 

 regions possess interesting dune areas, upon which various plant associations, 

 varying from pioneer herbaceous to chaparral and forest communities, have 

 become established. These communities are being mapped, permanent quad- 

 rats and transects established, and the underground portions of many species 

 excavated and studied. Measurements of evaporation, soil moisture, and soil 

 temperature have been made, and material collected for anatomical studies. 

 MacDougal and Spoehr are conducting investigations to discover the 

 origin of xerophytism in plants, and Mrs. Shreve has records extending over 

 several years of seasonal changes in the water relations of such desert plants 

 as Encelia farinosa, Streptanthus arizonicus, and Amaranth us Palmeri. 



Geo. D. Fuller. 



11 MacDougal, D. T., Ecology. Carnegie Inst. Wash. Year Book for 1919. 

 18:87-102. 1920. 



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