1917] AGRICULTURAL BOTANY. 129 



is stated that aqueous solutions containing fine particles can be passed through 

 the membranes of the bordered pits of sapwood from the stems of these and 

 other conifers, also that gases can be readily forced through bordered pits 

 thoroughly saturated with sap. The surface tension of sap in the pit membranes 

 can in some cases, it is claimed, be overcome by pressures of less than 3 atmos- 

 pheres. This is thought to disprove the tension hypothesis, according to which 

 a tension of from 5 to 20 atmospheres is required to maintain continuous col- 

 umns of water in trees. 



Relation of transpiration to assimilation in steppe plants, V. S. Iljin 

 (Jour. Ecology, 4 {1916), No. 2, pp. 65-82). — The author, reporting in consider- 

 able detail on another phase of the work previously noted (E. S. R., 33, p. 628), 

 claims that the experiments herein described show simply that we may expect 

 to find in drought-resistant plants a more economical evaporation of water. 



Recent developments in the study of endotrophic mycorrhiza, M. C. Ray- 

 NER (New Phytol, 15 (1916). No. 8, pp. 161-115). — This is a review of recent 

 studies and views on endotrophic mycorrhiza and a discu.s.sion of their bearing 

 on current conceptions of the physiology of the relationship and of their sig- 

 nificance in experimental ecology. 



The view held by the author is that the phenomenon of mycorrhiza in plants 

 is only an expression of the warfare waged continually by all organisms against 

 parasitic invasion of their tissues. The flowering plant possessing mycorrhiza 

 not only has checked the invading fungus, but has turned the invasion to its 

 o^'n advantage. 



Studies in the physiology of tlie fungi. — I, Nitrogen fi.xation, B. M. 

 DuGGAE and A. R. Davis (Ann. Missouri Bot. Gard., 3 (1916), No. 4, pp. 413- 

 Jf37). — This is the first report of a series of several studies now in progress on 

 the physiology of the fungi. Tabular details are given of the results obtained 

 from a study of nitrogen fixation. This was not established for Aspergillus 

 niger, Macrosporium commune, Penicillium. digitatum, P. expansum, and Glo- 

 merella gossypii, but cultures of Phoma betce on mangel and on sugar beet 

 decoction with sugar showed a nitrogen gain, which is considered to prove 

 definitely that nitrogen fixation occurs. Comparative studies of Azotobacter 

 strains indicate the usual relatively large fixation of nitrogen by that organism. 



Studies in the physiology of the fung'i. — II, Lenzites sepiaria, with special 

 reference to enzym activity, S. M. Zeller (Ami. Missouri Bot. Gard., 3 (1916), 

 No. 4, PP- 439-512, pis. 2). — This article, continuing the series indicated above, 

 is an account with discussion of studies on the wood-destroying fungus, L. se- 

 piaria, as regards the behavior of this fungus when grown in pure cultures on 

 selected media. The fungus grows well on 50 per cent resin by weight (which 

 is said to be a proportion greater than that found in any coniferous wood), and 

 growth is not entirely Inhibited by 85 per cent resin. 



The metabolism of the fungus was studied through the agency of enzym ac- 

 tion, and this study is reported in some detail. A comparative study of 

 enzyms found in the sporophores and mycelium indicated that the important 

 metabolic processes are carried on chiefly in the vegetative organs in the case 

 of diastase, invertase, tannase, and cellulase, while the oxidases show greater 

 activity in the sporophores. 



The mitochondrial origin of rhodoxanthin, F. Moreau (Bui. Soc. Bot. 

 France, 62 (1915), No. 4-6, pp. 158-160). — Discussing observations made by 

 himself and other investigators, the author claims that rhodoxanthin may origi- 

 nate in a plastid or in a chondriosome without passing through a chlorophyll 

 stage. It is thought that mitochondria and plastids may fix certain substances 

 which they select from the protoplasm. These they transform later into 

 products, which may themselves be transitory or final, by means of modifica- 



