Junk 9, 1904J 



NA TURE 



"\"erv remarkable is the statement that in the case of 

 HvJrocyon forskali it was found advisable to keep a light 

 turning near the tank in order to prevent the fish from 

 injuring themselves by swimming violently against the 

 glass walls. 



As official publication issued at Colombo by the Govern- 

 ment printer contains a summary of Prof. Herdman's report 

 on the pearl oyster fisheries of the Gulf of Manaar, which 

 raav be considered as supplementary to the report on the 

 same subject published by the Royal Society in November 

 last, and already noticed in our columns. After referring 

 to the condition and e.Ktent of the oyster-banks, the present 

 report briefly points out the chief sources of injury to the 

 molluscs, after which reference is made to the mode of 

 formation of pearls, and the best methods of pearl-fishing. 

 The report concludes with a series of recommendations, 

 among which are comprised the substitution of dredging 

 (in many instances) for diving, and the advisability of the 

 appointment of a permanent naturalist. 



An apparent instance of mimicry of a most remarkable 

 type is recorded by Dr. A. Willey in Spolia Zeylanica for 

 April (vol. ii., part v.). The attention of Dr. Willey had 

 been directed by a correspondent to the striking resemblance 

 presented by one of the Cingalese fishes commonly known 

 as sea-bats {Platax vespertilio) to a decayed leaf, and soon 

 .after he had the opportunity of verifying this' statement 

 for himself. " I was walking," he writes, " along the 

 reef in the company of a fisherman carrying a net when he 

 ■espied a small fish, which he attempted to catch for me. 

 I could not see what it was at first, but noticed that the 

 man failed to bag it after several ineffectual attempts. The 

 fish did not swim far away from the spot, but dodged about, 

 laffiing its pursuer. I approached and seized the net, 

 whereupon I saw a yellow jak-leaf gently and inertly sink- 

 ing to the bottom. This is no unusual sight, and I was 

 .about to turn away, when the leaf righted itself and darted 

 off. Efforts were redoubled and the fish secured and 

 sketched. . . . When a fish has a leaf-shaped and leaf- 

 coloured body, and in addition the unique habit of toppling 

 over and feigning death when pursued, it seems natural to 

 conclude that it is a genuine example of protective re- 

 semblance. " 



M.\xv of the visitors to Kew Gardens who take a special 

 interest in the orchid houses will be interested to know that 

 a revised edition of the " Kew Hand-list of Orchids " has 

 teen published, with the usual interleaved blank pages to 

 facilitate the jotting down of notes. The increase in the 

 number of genera, at any rate in the plants shown in the 

 houses, has been very evident, and the catalogue gives a 

 total of 220 for the collection. 



Thf. large proportion of economic questions which occupies 

 the attention of the botanical departments in our colonies 

 is well shown in the Bulletins (January, April) of the 

 Botanical Department in Trinidad. A striking analysis of 

 samples of sugar canes grown in Florida is quoted in an 

 extract, in w'hich no reducing sugar was found. The 

 proportion of the sugars in canes is not only important 

 from a commercial point of view, but as a purely scientific 

 ^juestion is well worth investigating. The recommend- 

 ation of carbon bisulphide as an insecticide affords evidence 

 of the spread of scientific knowledge amongst planters. 

 Other useful articles refer to prussic acid in cassava, rubber 

 analvses, and treatment of " black pod " on cacao estates. 



NO. 1806, VOL. 70] 



Prof. Eriksson returns to his mycoplasm theory, which 

 asserts that lUst fungi can hibernate in a protoplasmic form 

 in the leaf-cells of the host, in a paper which appears in the 

 TrnnsactioHs of the Royal Swedish .'Vcademy of Sciences, 

 vol. xxxvii., part vi., January. The investigations which 

 were carried out by Dr. Eriksson and Dr. Tischler consisted 

 in collecting the leaves of varieties of wheat which are liable 

 to rust, and examining them both in late autumn and the 

 following early summer, when no fungal mycelium could 

 be observed, but in certain cells the authors distinguished 

 a special dense accumulation of protoplasm, the mycoplasm. 

 I^ater in July, intercellular fungal tubes were found which 

 gradually developed into the ordinary hyphte. The change 

 from the mycoplasmic to the intercellular condition which 

 is assumed still requires confirmation. 



Mr. C. Fox-Str.\ngw.\vs has prepared a second edition 

 of his memoir on the Oolitic and Cretaceous rocks south 

 of Scarborough (Geological Survey, price 4s. 6d.). More 

 than twenty years have elapsed since the first edition was 

 published, and opportunity has been taken of adding a 

 series of pictorial views illustrating the fine cliff-sections, 

 while the subject-matter is amplified throughout. The 

 results of recent researches on the Speeton Clay are in- 

 corporated, and the author has dealt more fully with the 

 interesting topics of scenery and denudation. 



In an article on recent changes in the elevation of land 

 and sea in the vicinity of New York City, and from a study 

 of tidal observations on both sides of the Atlantic, Mr. 

 G. W. Tuttle (Ainer. Journ. Sci., May) comes to the con- 

 clusion that the mean sea-level oscillates in an irregular 

 manner, having an average period of about eight years. 

 These oscillations appear to be largely due to changes in 

 atmospheric pressure, and the resulting changes in wind 

 velocities. In addition to the above movements, Mr. Tuttle 

 finds that some ports show a more or less continuous rising 

 of the sea relatively to the adjacent land, others a lowering 

 of the sea-level in its relation to the land, and still others 

 maintain a constant relation between the two. These last 

 make it clear that, except for the periodic changes noted 

 above, the sea does not change its level, and that the re- 

 lative changes are due to land movements. Observations 

 at New York City show that since 1875 the land has been 

 subsiding at about 145 foot per century. 



Messrs. Philip H.akris .\nd Co. have sent us a pamphlet 

 giving a descriptive account of some new models and 

 apparatus to be used in teaching the measurement of 

 volumes, designed by Mr. S. Irwin Crookes. 



.Messrs. Watts .•\nd Co. have published for the Rationalist 

 Press Association, Ltd., a pamphlet entitled " What to 

 Read : Suggestions for the better Utilisation of Public 

 Libraries," which contains the substance of an address 

 delivered by Mr. John M. Robertson. Many useful hints 

 to parents and librarians who wish to develop in children 

 a love of reading and a regard for good books may be 

 gathered from the address. The price of the pamphlet is 

 fourpence. 



With the growth of the Stassfurt industries and the 

 increasing application of potassium salts in agriculture, a 

 rapid method of estimating potassium has become a question 

 of some importance. In the May number of the Gazzctta, 

 N. Tarugi describes a volumetric method of estimating the 

 element which depends on its precipitation in the form of 

 the sparingly soluble persulphate. The method is accurate. 



