30 EXPERIMENT STATION RECORD. [Vol.36 



tissue, and the failure of negative pressure is the cause of the decrease or cessa- 

 tion or withdrawal of water from the root. Higher negative pressures give a 

 greater flow than lower, but the increase does not bear a simple proportion to 

 the change in pressure. The flow from the cut stump may be greatly weakened 

 in spite of increased negative pressure by cooling the lower part or immersing 

 it in water or hydrogen. 



The separated top, immediately and for a while after its separation, shows 

 a considerable increase of water uptake, indicating that tensions exist in the 

 intact plant. These afterwards reach a state of equilibrium in connection with 

 the atmospheric pressure on the cut surfaces and the attainment of a uniform in- 

 flow of water, which some plants maintain for some time under constant tem- 

 perature. 



Studies on the decomposition of cellulose in soils, I. G. McBeth {Soil Set., 

 1 (1916), No. 5, pp. 437-^87).— This paper deals mainly with bacteria which 

 dissolve cellulose, a considerable number of which were found in the 69 soils 

 of southern California examined by the author. In working out descriptions 

 of new species, a number of which are systematically discussed, an attempt is 

 made to bring out individual characteristics as concisely as possible. A sum- 

 mary is given of the more important morphological and cultural features of 

 the bacteria. 



The cellulose agar plate method is said to be the most satisfactory for 

 isolating pure strains of bacteria, filamentous fungi, and Actinomycetes, which 

 dissolve cellulose and all of which grow under anaerobic, but luucli bet- 

 ter under aerobic, conditions. Filamentous fungi are thought to play a much 

 more important part in cellulose destruction in the humid soils of the eastern 

 part of the United States than in the semiarid soils of southern California, 

 wheie the rapid destruction of cellulose is thought to be due to favorable 

 climatic and cultural conditions rather than to the unusual activity of the cel- 

 lulose-dissolving soil flora. 



The primary sugar of photosynthesis, H. H. Dixon and T. G. Mason 

 {Nature [London], 97 {1916), No. 21,25, p. 160).— It is stated that while micro- 

 chemical tests on the assimilating cells of certain plants indicate a considerable 

 concentration of hexoses in the chloroplasts or in the protoplasm immediately 

 surrounding them, other lines of experiment suggest that while sucrose is con- 

 centrated in the large vacuoles invertase is held apart from it in the pro- 

 toplasm. 



Tlie view that the formation of sucrose is a preliminary step in the pro- 

 duction of hexoses in the leaf is not considered a necessary deduction from the 

 work of some other investigators named. It is thought more probable that the 

 liexoses are formed from formaldehyde in the chloroplast, and that at a cer- 

 tain concentration condensation into sucrose takes place due to invertase or 

 some saccharogenic enzym, the sucrose thus formed being passed into the 

 vacuole and stored there. The volume of the protoplasm available for the 

 hexoses being small as compared with that available for sucrose, the increase 

 In tlie total percentage of the hexoses formed will be relatively small on ex- 

 posure of the leaf to light as compared with the Increase in sucrose. This Is 

 therefore regarded as insufficient proof of sucrose being the primai-y sugar. 

 The recognition of the localization of the various substances in the cell is con- 

 sidered to furnish an explanation as to how the sucrose-hexose ratio of the cell 

 is maintained in the presence of invertase. 



The biochemical function of magnesium in plants, L. Bebnardini {Ann. R. 

 Scuola Sup. Agr. Portici, 2. ser., 12 {1914), PP- S61-S89).—lt is thought that 

 magnesium in connection with calcium plays an important part in the process 

 of vegetative growth in relation to the assimilation of phosphoric acid and in 



