December 19, 1912] 



NATURE 



441 



The November number of The American Museum 

 Journal contains a beautifully illustrated article by 

 Mr. G. B. Sudworth on the present condition of the 

 big-trees (Sequoia) of California. Thirty-one groups 

 of these trees, covering areas ranging from less than 

 an acre to ten square miles, and collectively occupy- 

 ing about fifty square miles, are known. Some of 

 these tracts are in private hands, while others belong 

 to the Federal Government, and it is urged that the 

 splendid grove in North Calaveras should be acquired 

 by Government. In the groves belonging to Govern- 

 ment no felling, except when absolutely necessary, 

 is permitted, but in those in private hands "lumber- 

 ing " is carried on to a greater or less extent. The 

 great danger to these trees is iire. The opinion has 

 been expressed that the Sequoias are not reproducing 

 themselves, and it seems that the seeds will not ger- 

 minate in ground thickly covered with vegetable 

 debris, or in deep shade. It is stated, however, that 

 "wherever in the southern groves lumbering and fire 

 have opened up the forest and exposed the mineral 

 earth, an abundance of young big-trees is always 

 found near seed-trees, unless, of course, fire has 

 destroyed them." 



Prof. H. Molisch has revised and enlarged his 

 well-known work on luminosity in plants (" Leuch- 

 tende Pflanzen," Gustav Fischer, Jena, price 7.50 

 marks). Since the publication of the first edition 

 (reviewed in Nature, November 23, 1905) various 

 writers — notablv Prof. Molisch himself — have contri- 

 tributed to this interesting branch of plant physiology, 

 and these scattered contributions are now brought 

 together, with references to the literature of the sub- 

 ject. A large portion of the work is devoted to the 

 phenomena of luminosity due to bacteria and fungi, 

 though the various "phosphorescent" phenomena 

 observed in animals and in the higher plants are dis- 

 cussed. Molisch concludes that the luminosity of 

 plants (from which, of course, are excluded various 

 cases of luminescence due to reflection of light brought 

 to a focus by lens-shaped cells, and the like) is due 

 to the production in the living cell of a substance 

 (" photogen ") which becomes luminous in the presence 

 of water and free oxygen, and that this substance is 

 either a protein or a phosphatid. The luminosity of 

 the luminous bacteria and fungi differs from the 

 various phosphorescent phenomena in animals in that 

 the light is continuous during life, and not inter- 

 mittent, though it may be due in all cases to a similar 

 cause — the oxidation of photogenic substances by 

 means of oxidising ferments. 



The Journal of Agricultural Science (vol v., part i) 

 contains, amongst others, a paper by Mr. W. A. Davis 

 on the estimation of potassium in fertilisers, soil 

 extracts and plant ashes. It is shown that the per- 

 chlorate method, of which a modification is suggested, 

 yields more accurate results than that in which 

 platinum chloride is used, and has the additional 

 adv'antages of (a) being more economical ; (b) the 

 results are not affected by the presence of barium, 

 calcium, and magnesium chlorides and sodium phos- 

 phate ; and (c) all uncertainty such as exists as to 

 what value shall be taken for the atomic weight of 

 platinum is avoided. 



NO. 2251, VOL. 90] 



In addition to the useful latest reports of ice given 

 in the monthly meteorological charts of the North 

 Atlantic Ocean issued by the Deutsche Seewarte, that 

 for December contains the commencement of a series 

 of air and sea temperature observations extracted 

 from the log-books of Transatlantic steamers in the 

 region of drift ice. The extracts, arranged according 

 to groups, include (i) observations of great fluctua- 

 tions of temperature ; (2) ice encountered without 

 much change of temperature ; (3) great decrease of 

 temperature indicating proximity of ice. During 1912 

 more than ordinary attention has been directed to the 

 danger of ice, owing to the unusual extension of its 

 distribution and to its density. In the case of fog 

 the only means of detecting ice, in addition to a more 

 careful outlook, is the observation of air and sea 

 temperature, but it has been shown that such data 

 are at times untrustworthy. The collection and pub- 

 lication of these extracts are, we consider with the 

 Seewarte, of considerable utility, as affording data 

 for a careful examination of the behaviour of tem- 

 perature in the drift-ice region, independently of 

 whether or not ice was actually met with. 



The report of the census of the island of Mauritius 

 and its dependencies for 191 1 has just been received. 

 The population is practically stationary as compared 

 with 1901, the slight decrease in the case of the main 

 island being balanced by an almost equivalent increase 

 in the dependencies. About 29 per cent, of the popu- 

 lation are included under the term " general popula- 

 tion," about I per cent, are Chinese, and the rest are in- 

 cluded as Indo-Mauritians or other Indians; the latter 

 class includes Indians born out of the colony, whom 

 it is becoming increasingly difficult to distinguish from 

 Indo-Mauritians. Fewer people are returned as 

 engaged in industrial occupations ; there has been an 

 increase in the males who are agriculturists, and 

 in the females who are domestics, but a decrease in 

 the male domestics, in the general population, while 

 the Indian population has become more definitely com- 

 mercial and industrial at the expense of agriculture 

 and domestic service. The report includes a map on 

 the scale i in. = i mile, showing the geographical dis- 

 tribution of the people. The Census Commissioner 

 has also published a study in Mauritian statistics 

 which deals with "agricultural labour." This study 

 necessarily refers almost exclusively to the sugar in- 

 dustry, and points out that the position of the Indian 

 labourer is "one of unusual prosperity," since labour 

 is scarce; sugar yields are abnormally high, and 

 prices are remunerative. 



A SUMMARY of the agricultural statistics for British 

 India for the quinquennium ending with the season 

 1910-11 has just been issued by the Indian Govern- 

 ment. The percentages of the area of British India 

 for this and the preceding quinquennium show an 

 approximately constant subdivision as follows : — 

 Forest, 13 per cent. ; not available for cultivation, 25 

 per cent. ; culturable waste, 19 per cent. ; current fal- 

 low, 7 per cent. ; net area cropped, 36 per cent. 

 Roughly 17 per cent, of the cropped area, which is 

 sometimes cropped twice, is irrigated. About go per 

 cent, of the cropped area is constantly devoted to food 



