September 23, 1922] 



NA TURE 



429 



Research Items. 



The Date of Stonehenge. — In the September 

 issue of Man Rear-Admiral Boyle T. Somerville dis- 

 cusses a previous article in that journal by Mr. Stone 

 on the date assigned by Sir Norman Lockyer, through 

 astronomical means, for the building of Stonehenge. 

 He points out in detail the limitations which surround 

 the dating of prehistoric monuments by means of 

 bearings of sunrise or sunset. There are also at 

 Stonehenge two circles, one apparently considerably 

 more ancient than the other. Neither of these stands 

 on the arc of a true circle, and consequently it is not 

 possible to discover the accurate centre, nor any given 

 diameter of either of them. The remains of the 

 earthwork vallum do not lie on parallel lines, nor does 

 either wall appear to be straight. A difference of 

 date of 1000 years is effected b)' the movement of the 

 observer of only one foot to left or to right of what 

 may originally have been the true point of observation 

 within the circle. The result is that the attempt to 

 date either of the circles at Stonehenge by the azimuth 

 of the midsummer sunrise is useless, as the present 

 condition of ruin of the monument is too great to 

 lay out from the ground-plan of either circle an 

 orientation line of sufficient accuracy. If the 

 orientation towards Silbury Hill can be considered 

 a probability, as it was by Sir Norman Lockyer, the 

 limits of date given by him, namely 200 years on 

 either side of 1680 B.C., are justified for whichever 

 circle to which it related. 



Arab Art in America. — The University Museum, 

 Philadelphia, is in the fortunate position of being able 

 to spend largely on additions to its collections. In 

 the March issue of its Museum Journal, Mr. G. B. 

 Gordon describes some examples of Arab art which 

 have recently been acquired. Two mosaic fountains 

 of fifteenth - century work are charming, and are 

 appropriately placed in a room decorated with a 

 wonderful wooden door with carved ivory inlay from 

 fourteenth-century Cairo. The ornamentation of this 

 door is singularly beautiful, the style combining small 

 pieces dove-tailed together, the result of the scarcity 

 of large blocks of suitable wood in Egypt. There 

 are also some examples of Rhodian, Damascus, and 

 Samarkand tiles, which are finely reproduced in 

 colour to illustrate the article. Mr. Gordon gives 

 some useful notes on the development of Arab art, 

 especially in connexion with the taboo of human and 

 animal forms prescribed in Islam. At Fostat, near 

 Cairo, a rubbish heap in the town, abandoned in the 

 thirteenth century for the present capital, has yielded 

 some curious fragments of early Arab pottery, of 

 which examples are also reproduced in colour. 



Origin of Animal Pigments. — That animals in 

 general are, directly or indirectly, dependent upon 

 green plants for their supplies of energy is one of the 

 most widely recognised generalisations of biological 

 science. The importance of chlorophyll in the 

 animal economy, however, seems to be by no means 

 limited to the problem of food-supply. It is extremely 

 doubtful whether chlorophyll is ever actually formed 

 by the animal body itself, but it is very extensively 

 taken in with vegetable food, and then apparently 

 forms the basis from which a large number of animal 

 pigments are built up, including the widely distributed 

 respiratory pigment, haemoglobin. Such, at any 

 rate, is the finding of Mr. John F. Fulton, Jr., who 

 contributes an interesting paper on " Animal Chloro- 

 phyll : its Relation to Haemoglobin and to other 

 Animal Pigments " to the current number of the 



Quarterly Journal of Microscopical Science (vol. 66, 

 Pt. II.). It would appear from these results that 

 a vast number of animals are dependent upon green 

 plants for their ability to carry on the function of 

 respiration as well as that of nutrition. 



Sources of Vitamin A. — In the Biochemical 

 Journal (vol. xvi., No. 4) a paper appears under the 

 names of H. L. Jameson, J. C. Drummond, and 

 K. H. Coward, giving an account of the work in 

 which Dr. Jameson was engaged at the time of his 

 death. Previous work by the other two authors had 

 shown that vitamin A is produced in green plants by 

 the action of light. Animals are apparently unable 

 to make it for themselves, and since the liver of fishes 

 is one of the best sources of this vitamin, it was of 

 interest to follow the course of its transfer to this 

 place. In the present paper it is shown that a pure 

 culture of the diatom Nitzschia produces the vitamin 

 under the action of light. Various molluscs were also 

 found to contain it in considerable amounts. In a 

 further paper in the same number of the journal, 

 Prof. Drummond, Dr. Zilva, and Miss Coward show 

 that the small organisms of animal nature making up 

 the plankton on which small fish feed contain vitamin A 

 in abundance, no doubt derived from the diatoms 

 on which the plankton feed. Thus the cycle in marine 

 life is complete. Whether this vitamin is identical 

 with that preventing the onset of rickets is made 

 somewhat doubtful by a paper in the Journal of 

 Biological Chemistry, vol. 53, p. 293, by McCollum, 

 Simmonds, Becker, and Shipley, in which it is shown 

 that the vitamin A of cod-liver oil can be destroyed 

 without depriving the oil of the substance which 

 causes utilisation of calcium and its deposition in 

 the bones. It may be that it is this " vitamin " that 

 is produced in the human infant under the action of 

 light. 



Anomalous Storm Tracks. — A communication is 

 made on this subject to the U.S. Monthly Weather 

 Review for March by Mr. E. H. Bowie of the U.S. 

 Weather Bureau. The author criticises the explana- 

 tion of the paths of cyclones given in the text-books, 

 and remarks that it would simplify the work of fore- 

 casters if cyclones behaved in an orderly manner. 

 The paths are shown of five exceptionally erratic 

 cyclones, and especial care has been taken to ensure 

 the accuracy of the charted positions of the storm 

 centres. The erratic paths given traverse the eastern 

 United States ; one storm was of West Indian origin. 

 Each of the tracks formed one or more loops, and in 

 forming the loop the turning in all cases was counter- 

 clockwise. Some notes on the erratic paths of the 

 storms are added by Prof. A. J. Henry, chiefly with 

 the object of stimulating discussion. He notes that 

 the temporary blocking in the path of the cyclone 

 takes place in the neighbourhood of water surface, 

 and in each case of temporary blocking, except in 

 that of the West Indian storm, pressure rose over 

 the Canadian Maritime Provinces. 



Climate and Photography. — An article 1>\ Mr. 

 H. G. Cornthwaite on this subject appears in the 

 U.S. Monthly Weather Review for March. The wide 

 variations in the strength of daylight with the time 

 of day, season of the year, conditions of the sky, 

 and with latitude and altitude, as well as the effects 

 of temperature and humidity on photographic and 

 chemical processes, are recognised and discussed. 

 ! The actinic light is naturally brightest when the sun 



NO. 2760, VOL. HO] 



