208 SCIENCE PROGRESS 



in plants is made by Willstatter and Stoll (Berichte, 191 7, 

 50, 1777). The assumption originally put forward by Baeyer 

 in 1870 was that formaldehyde was the intermediate com- 

 pound between carbon dioxide and the carbohydrate ; this 

 view has been frequently attacked in recent years, and other 

 compounds, such as oxalic or glycollic acids, have been sug- 

 gested. According to the present authors formaldehyde is 

 the only likely compound in the formation of which the volume 

 of carbon dioxide absorbed is equal to the volume of oxygen 

 liberated. The assimilatory quotient C0 2 /0 2 for formaldehyde 

 is 1, for glycollic acid it is 1*33, and for formic and oxalic acids 

 it is 2 and 4 respectively. This quotient has now been accur- 

 ately determined for a variety of different leaves, both ordinary 

 foliage and the succulent leaves of the cactus ; within a 

 temperature range from 10-35 the figure has been found in 

 every case to be unity whether the atmosphere was rich in 

 carbon dioxide or deprived of oxygen altogether, thus form- 

 ing a remarkable support for the accuracy of Baeyer's theory. 



GEOLOGY. By G. W. Tyrrell, A.R.C.Sc, F.G.S., University, Glasgow. 



Geological Processes. — Chamberlin, T. C, Diastrophism and 

 the Formative Processes, IX., A Specific Mode of Self-pro- 

 motion of Periodic Diastrophism, Journ. Geol. 1918,26, 193-7. 



W. M. Davis reviews the whole question of coral reefs and 

 submarine banks with reference to Darwin's theory of inter- 

 mittent subsidence, and the glacial-control theory of Daly, which 

 he regards as the only theories of reef formation deserving con- 

 sideration at the present stage of the controversy (Journ. Geol. 

 191 8, 26, 198-223 ; 289-309 cont.). The general result of the 

 discussion is that the long-enduring stability of reef founda- 

 tions, and the abrasion of reefs and islands by the chilled 

 and lowered glacial ocean, as demanded on Daly's view, are 

 very improbable. Coral reefs are believed to be better ex- 

 plained by subsidence and aggradation than by stability and 

 abrasion. Subsidence of considerable amount, aided by small 

 changes of ocean level, have determined the conditions under 

 which present-day sea-level reefs have been formed. 



Cotton, C. A., Conditions of Deposition on the Conti- 

 nental Shelf and Slope, Journ. Geol. 191 8, 26, 135-60. 



H. Dewey demonstrates the existence of a former upland 

 plain of wide extension in Carnarvonshire, terminating at a 



