<60 SUMMAEY OF CUERENT RESEARCHES RELATING TO 



""luminous," cave-growing moss is 0*02-0 '002 (Bunsen's unit), the 

 protonema thriving well even in so feeble a Hght as 0*008. The shoot, 

 "however, never grows where light is 0*001 or below it. 2. In the dark 

 the protonema can live for seven months at least without producing a 

 leaf or shoot. Where the light exceeds 0*1 the moss cannot live. 3. 

 The movement of the chromatophores is slow. When the protonema is 

 placed in the light the chromatophores are scattered in a day ; and 

 -when the direction of light is changed they all turn towards it in seven 

 to ten days at a temperature of 15°-25° C. 4. The spherical cells of'the 

 protonema seem to enable the moss to ■efiFect assimilation in a feeble 

 light. 5. The moss thrives better, and the movement of the chromato- 

 phores is quicker, in a blue or violet light. 6. The optimum temperature 

 for the development of the shoot is 16°-25° C. The minimum life 

 temperature for the shoot is -IS^'C, and for the protonema is 

 -20*5°C. 7. The optimum humidity of the air is 90 to 100 p.c. 

 :8. The protonema is strongly adapted for resisting desiccation. 9. As 

 ^ cultural medium EUe and Emile Marchal's solution is the best. 10. 

 The nitrate, sulphate, chloride and carbonate of calcium, each in * 1 p.c. 

 solution, are not only not injurious to Schistostega osmundacea, but 

 stimulate its growth to a certain extent. 11. The spore, at temperature 

 16°-25°C.. germinates in one month, and its first filament has a cylin- 

 drical shape, producing many spherical cells soon after. 



Mosses Collected by the Smithsonian African Expedition. — H. N. 

 Dixon (Smithsonian Miscellaneous Collections, Washington, 1918, 69, 

 No. 2, 28 pp., 2 pis.). An account of the mosses collected in 1909-10 

 by E. A. Mearns on Mount Kenia, with an introductory discussion of 

 the moss-flora of the mountains of East Tropical Africa. Of the forty- 

 €ight species collected, twelve proved to be new to science, and their 

 -characters ai-e described and figured. A. G. 



Thallophyta. 

 Algse. 



Microbiological Researches on some Japanese Water-supplies. — 

 H. Hattori (Journ. Coll. Sci. Imper. Univ. Tokyo, 1917, 40, art. 4, 

 76 pp., G pis.). The author has made a full investigation into the 

 principal water systems of Japan, especially that in Yokohama, in order 

 to ascertain how the different species and the development of the bacteria 

 affect the quality of the water ; to what extent the flora of the superficial 

 •covering of dirt is of importance in the examination of the water ; and 

 •whether the speed of filtration could be hastened. The results of the 

 work are set forth in detail and illustrated by tables. The species which 

 ■compose the superficial covering consist of Diatoms, Chlorophyceae, 

 -Conjugate and Schizophyceaj, which show annual fluctuations. The 

 rich algal vegetation assists in the work of filtration, but it offers no 

 liindrance to the development of bacteria in the water. Four plates of 

 figures are given of the algas. A large part of the paper is devoted to 

 ^he bacteria. E. S. G. 



