138 



NATURE 



[March 31, 19 10 



of the body, as it is unreasonable to suppose that any por- 

 tion of the skin of an armoured reptile would be unpro- 

 tected. As regards the great vertical dorsal plates and 

 caudal spines, the former of which Marsh regarded as 

 forming a single series, it is practically certain that all 

 were arranged in a double row. The vertical plates are 

 considered to be nothing more than an ultra-development 

 of the longitudinal vertical ridge on the horizontal scute 

 of a crocodile or an unspecialised dinosaur like Ancylo- 

 saurus. Throughout the back the ribs are T-shaped in 

 section in order to bear the weight of the plates. In the 

 neck the latter are borne on short and notched transverse 

 processes, but in the back these processes become longer 

 and stouter, while in the sacral and anterior caudal region 

 the bases of the plates are approximated and supported 

 on the summits of the tall and expanded neural spines. 

 On the other hand, the terminal third of the tail apparently 

 formed a flexible aggressive weapon, in which the laterally 

 divergent spines were inserted in the muscles between the 

 neural spine and the centrum. Although the caudal spines 

 of the English Kimeridgian Omosaurus or Dacentrus are 

 structurally identical with those of one of the American 

 species of Stegosaurus, in the lack of evidence as to the 

 presence of vertical plates in the former the author is in- 

 disposed to admit the generic identity of the Old World 

 and American t3'pes. 



Dipterocarpus tuberculatus, known locally as the In 

 tree, one of the most important members of the family 

 Dipterocarpacese which bulks largely in the Burmese 

 forests, forms the subject of a Forest Pamphlet (No. 13) 

 compiled by Mr. R. S. Troup, and published by the Govern- 

 ment of India. As a rule, it is a dominant tree, and an 

 idea of its characteristic gregariousness may be obtained 

 from computations, which estimate fifteen to twenty good- 

 sized trees per acre. Fine specimens attain a height of 

 90 feet, with a clean bole of 60 feet and a girth of 

 10 feet. The wood is resinous and heavy, requiring 

 bamboos if it has to be rafted; it is in considerable 

 demand, as it works well, but is not durable if exposed. 



A RECENT paper by Prof. G. Klebs, published in the 

 Sitzungsberichte der Heidelberger Akademie der Wissen- 

 schaften (part v., 1909), and obtainable as a separate 

 brochure, describes the modifications produced in flowers 

 of Sempervivum when exposed to special cultural condi- 

 tions, and incidentally contains some pertinent opinions on 

 the subjects of variation in plants and inherited characters. 

 The species, S. acuminatum, chosen for experiment is a 

 recognised natural species. Plants were grown in rich soil 

 and kept at a high temperature. The first inflorescences 

 were cut off when quite young, and dormant inflorescences 

 showing abnormalities were developed, from which self- 

 fertilised seed was collected. Plants raised from the seed 

 were grown, and increased vegetatively for three years. 

 On flowering, the terminal inflorescences were removed 

 as before, and the later flowers produced abnormalities, 

 some new, others similar to those obtained before. These 

 abnormal characters the author recognises as pathological 

 modifications, yet regards their origin as intermediate 

 between fluctuating variations and mutations. 



Mr. T. Petcii is responsible for three recent Circulars 

 (vol. iv., Nos. 21—3) dealing with fungus diseases, issued 

 from the Rojal Botanic Gardens, Ceylon. A bark disease 

 on Hevea and tea that appears during the south-west 

 monsoon is attributed to Corticium javanicum. A more 

 insidious disease of Hevea, known as " die-back," is 

 started by a Gloeosporium which paves the way for 

 the destructive parasite, assigned to the genus Lasio- 

 diplodia. The third pamphlet discusses very fully the 

 NO. 2109, VOL. 83] 



stem-bleeding disease of the cocoa-nut caused by 

 Thielaviopsis aceiicus, a known parasite on sugar-cane in 

 Java. The author communicates a number of details re- 

 garding the structure of the cocoa-nut palm. He dis- 

 tinguishes two types of tree, the one with a uniform 

 columnar base, the other with a swollen base, and suggests 

 that the latter, which is the less desirable, has been selected 

 unconsciously by planters. 



According to the AgricuUural Journal of Ihe Cape of 

 Good Hope, a certain amount of work on the hybridisation 

 of wheat is being done in Cape Colony. At present less 

 than half the wheat required for consumption is grown, 

 the rest being imported ; steps are therefore being taken 

 to increase the area under crop. One of the chief difficul- 

 ties about wheat-growing in the colony, and particularly 

 in the western provinces, is the vast amount of destruction 

 caused by rust ; indeed, this was at one time so serious 

 that farmers almost despaired of making wheat-growing a 

 success. The importation of certain varieties more or less 

 resistant to rust rather relieved matters, but none has yet 

 been found fully to meet the local requirements. A cross 

 between Gluyas and Darling promises to give useful 

 results ; Gluyas is resistant to rust but possesses very 

 weak straw; Darling, on the other hand, possesses 

 exceptionally strong straw. A hybrid. Union, has been 

 picked out possessing strong straw and also resistant to 

 rust. Another promising cross is , between Gluyas and 

 Du Toits, probably the finest milling wheat in the colony. 



In the Sitzungsberichte of the Vienna Academy of 

 Sciences (Bd. cxviii., Heft vii.) P. Vujevic discusses at 

 some length the results of five years' temperature observa- 

 tions (1902-6) made at Belgrade. The readings were taken 

 from freely exposed mercury thermometers, with cylindrical 

 bulbs, at the earth's surface and at 0-4, 10, and 20 m. above 

 it. The results are of special interest in view of the plea 

 for such observations recently put forward in this country. 

 The excess of the mean temperature from hourly readings 

 of the freely exposed thermometer at 2 m. above the mean 

 temperature in the screen at the same height is —01° C. 

 in January, +06° in July. The mean difference is greatest 

 ( + 20° C.) at I p.m. and least (—10° C.) at 8 p.m., in 

 both cases in July. The occurrence of the minimum differ- 

 ence immediately after sunset is attributed to the retention 

 of warm air in the screen. It is probably also due in part 

 to the heat capacity of the screen itself. The point is of 

 importance in connection with the analysis of the daily 

 variation of temperature. Comparisons showed that the 

 freely exposed thermometers gave higher readings at all 

 levels on clear days, and lower readings on a cloudy day, 

 than the aspirated thermometer of the Assmann instrument. 

 The disturbance of the natural condition by the artificial 

 aspiration would have some influence on these results. The 

 observations from the freely exposed instruments are com- 

 pared with one another without any attempt at correction. 

 Throughout the year the temperature at the earth's surface 

 is lower by night and higher near mid-day than that in 

 the air. The extreme differences between the hourly means 

 for surface and air are approximately -I- 1-5°, —0-5° C. in 

 January, -f-9i°, — 1-6° C. in April, and -t- 152°, —10° C. 

 in July. Deposition of dew diminishes the value of the 

 negative difference, while clear weather increases both the 

 positive and negative differences. The temperature on the 

 exposed earth's surface was found to be considerably below 

 that of the neighbouring upper surface of snow. It is 

 assumed that the results are inter-comparable because the 

 thermometers are similar, an assumption which is npt 

 justified unless the ventilation is the same for each ; this 



