RECENT ADVANCES IN SCIENCE 557 



(see Compt. rend. Acad. Set. Paris, vol. clix, 191 9, pp. 1-2). 

 The same author recorded several fresh species of which the 

 anatomical structure was preserved in silica, from the famous 

 locality in the Vosges {Compt. rend. Acad. Sci. Paris, 1920, 

 pp. 250-52). 



A new genus of the Lepidodendreae was described by Horich 

 as Protasolaniis Wieprechti {Jahrb. Preuss. Geol. Landesanst, 191 9, 

 vol, xl, pp. 434-59, pis. xvi and xvii). A detailed study of the 

 flora of the Gilfach Goch region of South Wales has long been 

 on hand by David Davies, and one part of the results was pub- 

 lished in the Trans. Inst. Mining Engin., vol. lix, pt. 3, pp. 

 183-221, 1920. 



Coal. — Much work has been done in recent years, both in 

 this country and abroad, on the structure of coal, but Walcot 

 Gibson, in his book " Coal in Great Britain," lost a golden 

 opportunity of writing useful chapters on the structure of coal, 

 for he reiterated several old loose or inaccurate statements on 

 the subject, and omitted reference to the more recent and careful 

 chemical and palseobotanical work. A paper " On the Four 

 Visible Ingredients in Banded Bituminous Coal," by Stopes 

 {Proc. Roy. Soc. Lond., vol. xc, 191 9, pp. 470-87, pls. xi-xii), 

 described and differentiated four ordinarily visible portions in 

 typical coal. These were Fusain (or mother of coal) and the 

 three others to which new names were given, viz. Durain, 

 Clarain, and Vitrain. The differences in characteristics between 

 these were shown to exist also in chemical, physical, and 

 microscopic details. This paper has led to a great deal of 

 work by others on the further study of the four ingredients, 

 notably that by Tideswell and Wheeler on the chemical con- 

 stitution {Jour. Chem. Soc, 1919, vol. cxv) and by Lessing on 

 " The Behaviour of the Constituents of Banded Bituminous 

 Coal in Coking " {Trans. Chem. Soc, 1920, vol. cxvii, pp. 247- 

 56) and on their Mineral constituents (same volume, pp. 256- 

 65). Advance proof is to hand of more work on the theme, 

 but it is not yet pubhshed. The considerable differences in 

 plant-content, coking properties, water-content, and mineral 

 ash, etc., which all the above work reveals as existing in visible 

 zones in coal within a few inches or millimetres of each other 

 necessitate a fundamental revision of our conceptions of the 

 nature of coal as hitherto based on analyses and other results 

 obtained from " bulk " samples. 



PLANT PHYSIOLOGY. By Prof. Walter Stiles, M.A., University 

 College, Reading. (Plant Physiology Committee.) 



Carbon Assimilation. — During the last two years the literature 

 of photosynthesis has grown considerably. Investigations on 

 the relations of the various conditions of carbon assimilation 



