ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 217 



and leaves a resinous-looking residue. The colour is variously modified 

 by acids and alkalis. In another communication they give their observa- 

 tions on a yellow pigment furnished by a new species, A. Scheelii. It is 

 also insoluble in water but soluble in spirits, etc., the solutions being 

 fluorescent. It colours cotton and paper strongly, and is only slightly 

 modified by reagents. 



Relation of Parasitic Fungi to the Contents of the Cells of the 

 Host-plants.* — M. T. Cook and J. J. Taubenhaus have studied this 

 problem to find out as far as possible the reason of immunity to disease 

 in certain plants, especially with reference to the presence of tannin and 

 the extent of its toxic action. They made artificial cultures of fungi, 

 and introduced varying quantities into the cultures. They found that, 

 in general, tannin inhibited the growth of fungi, and also that the effect 

 of the poison was more pronounced in the case of parasitic than of sapro- 

 phytic fungi. Small amounts of tannin had a stimulative action on 

 the growth, but any increase had an unfavourable influence on spore- 

 germination. Spores grown on thin layers of cork penetrated through 

 to agar below, but if the cork were impregnated with tannin the hyphae 

 did not grow through. The authors hold that tannin in the cells may be 

 a cause of immunity in the host. 



Phosphorus-content of the Yeast-cell, j — E. Buchner and H. Haehn 

 experimented with yeast-cells, keeping them under water for a while, and 

 found that there was an excretion of phosphorus compounds. In crushed 

 yeast only about a third of the phosphorus is expressed, two-thirds remain 

 in the yeast-cell. The quantity of phosphorus in the resting-yeast varies, 

 and the authors could not determine if there was any connexion l;)etween 

 the amount of phosphorus present and the capacity for fermentation. 



Study of Edaphic Organisms. J— R. H. France, in examining the 

 minute flora and fauna of the soil, has made cultures from specimens of 

 earth from many localities. Along with bacteria, algte, and various in- 

 fusoria, he finds a fungus, CJadosporium hamifacieiis. The collective 

 organisms he calls the edaphon, corresponding to the plankton of water 

 organisms. The author points out the importance of edaphon in the 

 nitrification, etc., of the soil. 



Iron Fungi. § — Certain filamentous fungi that can store up iron in 

 theu" tissues are widespread in nature. The larger number belong to a 

 species of Gitromyces. Experiments with G. siderophilus made by 

 Rudolf Lieske showed that it grew like other filamentons fungi in a 

 culture solution without iron, but an addition of • 5 p.c. ferric sulphate 

 produced a decided increase in growth, while other fungi were un- 

 favouraltly affected. Other compounds of iron were tested with varying 

 results. These iron fungi take an important part in nature in laying 

 down ironstone. 



* Delaware Coll. Agrie. Exp. Stat., Bull. No. 91. See also Mycologia, iv. (1912) 

 pp. 42-4. 



t Bioch. Zeitschr , xxvii. (1910) pp. 418-26. See also Bot. Centralbl., cxviii. 

 (19111 p. 630. X Centralbl. Bakt.,xxxii. (1911) pp. 1-7. 



§ Jahrb. wiss. Bot. 1. (1911) pp. 328-54 (2 figs.). 



