September ii, 19 19] 



NATURE 



41 



little of the origin of the Doliolidae and Salpidae, the 

 comparative study of the manner of budding gives us 

 reason for believing that Doliolum arose from Pyro- 

 soma-like ancestors . . . and that from Doliolum-like 

 aricestors arose the Salpidas." 



A BRIEF systematic paper of exceptional distribu- 

 tional interest has lately been published by Prof. C. 

 Chilton in the A.nn. Mag. Nat. Hist. (9), vol. iii., pp. 

 376-386. He identifies specimens of a sandhopper col- 

 lected at Picton, New Zealand, with Fritz Miiller's 

 Orchestia tucttranna from South Brazil — a species 

 known to some naturalists not specialists in the Am- 

 phijxida through references in Miiller's "Pacts and 

 Arguments for Darwin," published in 1869. Another 

 South American Orchestia, O. chiliensis, had previ- 

 ously been recognised by Prof. Chilton on the New 

 Zealand coasts. 



The U.S. Department of .Agriculture has published 

 (Bull. 780) a pamphlet on Nosema-disease in bees by 

 G. F. White, who gives interesting facts as to the 

 resistance of Nosema spores to heat, drying, and other 

 adverse conditions. His observations as to the occur- 

 rence of Nosema in North America and its effect on 

 bees that harbour it will be valuable for comparison by 

 workers in these countries, though he believes that "it 

 is not possible to state whether the Isle of Wight dis-. 

 ease and Nosema disease [as present in America] are 

 one and the same disorder." He strangely neglects 

 the work of Fantham and Porter on the subject, barely 

 referring to their papers of 1911 (Proc. Zool. Soc. 

 Land.) and iqia (Suppl. Journ. Board Agric), and 

 ignoring their subsequent publications. 



The Carnegie Institution of Washington has 

 recently published the first volume of a memoir 

 entitled "The Cactaceae : Descriotions and Illus- 

 trations of Plants of the Cactus Familv," by N. L. 

 Britton and J. N. Rose. The svstem'atic studv of 

 succulent plants, such as the Cactaceae, is beset by 

 many formidable difficulties. As a consequence, such 

 study is far from general. Fortunately these difficul- 

 ties have always proved attractive to a select band 

 of workers gifted with that infinite capacitv for 

 taking pains which the peculiar exigencies of the 

 case dernand. .Among early authors who have earned 

 renown in this exacting field we may recall the names 

 of A. P. De Candolle with his artist colleague P. J. 

 Redoute, of -Adrian Henrv Haworth, and of Prince 

 Salm-Reifferschied-Dyck. The fit, if few, who labour 

 in this particular field to-day include no one whose 

 name is more honoured than that of the veteran 

 Mr. N. E. Brown. The volume now issued as 

 Publication No. 248 of the Carnegie Institution 

 shows that this chosen band of workers has been 

 augmented by the addition of two worthy recruits. 

 Their handsome and craftsmanlikc treatise, which 

 deals with the tribes Pereskie» and Opunticae. is 

 illustrated bv thirtv-six plates, of which twentv-eight 

 are coloured, and by 302 text-figures, many of them 

 reproduced from photographs. The thorough manner 

 in which the attendant difficulties have been over- 

 come by the careful study of type-specimens and 

 original descriotions, by the extensive collection of 

 living and of herbarium material, and by prolonged 

 field-observation, deserves the highest comrriendation. 

 The excellence of the illustrations and the lucidity 

 of the descriptions render the work one of the most 

 important contributions yet made to the taxonomy 

 and natural history of a family of succulent plants. 

 It should make relatively simple what has hitherto 

 been an exceedingly difficult task to the botanist and 

 to the cultivator. Both should now be able to identify 

 with some confidence many of the cactaceous plants 



NO. 2602, VOL. IO4I 



grown in European plant-collections, and to discard 

 from their lists a host of superfluous names which 

 have long encumbered our catalogues. Grower and sys- 

 tematist alike will look forward with keen expecta- 

 tion, and, indeed, with something like impatience, 

 to the appearance of the further volume in which 

 our authors are to deal with the Cerea;, the last of 

 the three tribes that compose the Cactaceae. 



The Tyndall lectures delivered by Prof. John Joly 

 before the Royal Institution in -April, 1918, have now 

 been published in pamphlet form with the title 

 "Scientific .Signalling and .Safety at Sea." The lec- 

 tures were devoted to two of the most urgent problems 

 which confront a sailor, viz. the determination of his 

 position upon near approach to the coast, and the 

 means of avoiding collision at sea, when owing to 

 thick weather, fog, or snow visibility is very low. 

 Until recent years the only aids the sailor had were 

 untrustworthy fog-signals, the use of the lead, and 

 the use of his steam-whistle. Sound is conveyed in 

 a very capricious way through the atmosphere. .Apart 

 from the effects of wind, which causes sound to carry 

 badly or to be inaudible owing to the noise and uproar 

 around a ship, large areas of silence are often found 

 in different directions and at different distances from 

 a fog-signal .station in calm weather. • In suite of these 

 circumstances, these time-Tionoured methods have been 

 of inestimable value. Prof. Joly suggests that the 

 time has now come when the resources of science 

 should be invoked to supplement the older methods. 

 He advocates the use of "synchronous signalling" — 

 this is, the use of signals' propagated in different 

 media, but timed so as to start at the same instant. 

 The particular system recommended is the combina- 

 tion of wireless signals with under-water sound 

 signals. Both methods of signalling are practically 

 indenendent of atmospheric conditions, and have a 

 much greater range than air-borne signals. The 

 difference between their speeds of propagation suffices 

 to determine the distance of the source and the use 

 of either a radio-goniometer or a directional hydro- 

 phone enables the direction of the source to be ascer- 

 tained. It is Dolnted out that the necessary wireless 

 apparatus is now available, and, thanks to the efforts 

 of the Submarine' Signal Co., efficient under-water 

 signalling apparatus, such as the submarine bell, 

 Fcssenden oscillator, hvdrophones, etc., are also ob- 

 tainable commercially. Several interesting apolirations 

 of the synchronous signalling method are given, and 

 the pamohlet is to be commended to all who have an 

 interest in those who go down to the sea in ships. 



Summer weather has this year at times proved very 

 disappointing, although August, which is the general 

 holiday month, was for the most part particularly fine. 

 -August was the warmest summer month ; the mean 

 temperature at Greenwich was 649°, which was 6° 

 warmer than July and 45° warmer than June. The 

 mean maximum temperature in -August was 75-6°, 

 and there were eleven days with the highest day tem- 

 perature above 80°, whilst in July the thermometer 

 failed to touch 80°, and in June that reading was 

 only attained on four days. The mean temperature 

 at Greenwich for the whole summer was 61-4°, which 

 is 1° warmer than the summer last year and nearly 

 3° warmer than in 1916. It is 34° cooler than the 

 memorable summer of 1911, which was more abnormal 

 than any summer of recent years, when in both July 

 and August the mean maximum or day temperature 

 was 81°. The weekly weather reports published by 

 the Meteorological Office show that the wannest 

 summer weather occurred during the weiek ending 

 .\ugust 16, when the mean temperature was 3° to 

 5° F. above the normal, and the maximum day read- 



