5i6 



NATURE 



[August 17, igib 



the post-larval stages of the fish have the size and 

 colour of fragments of weed, which often are found in 

 the waters which these young fish frequent. VVhen 

 alarmed, the fish become rigid and float about in an 

 apparently inanimate condition. When this occurs, it 

 is difficult to distinguish them from the pieces of weed 

 floating around. In klipfish {Clinus spp.) the young 

 are born alive, and they are of a clear, glassy trans- 

 parency difficult to detect in the water. The contour 

 of the body is probably disguised by a number of 

 minute dark dots. The colour pattern in other young 

 fish is shovv^n to be more marked and considerably 

 different from that of the adult. Some details of this 

 difference are enumerated in the cases of the Jeerfish 

 and the stockfish and a species of dogfish. It is indi- 

 cated how this colour pattern of the young fish may 

 be a form of protective resemblance. — H. H. W. 

 Pearson : Morphology of the female flower of Gnetum. 

 Much work has been done in recent years on the 

 morphology of the flower of the Gnetales, and very 

 diverse views have been put forward. These are dis- 

 cussed, summarised, and compared in this paper, with 

 special reference to recent investigations by the author 

 and to the conclusions of MM. Lignier and Tison, 

 both as published and as discussed in correspondence 

 with the author. Investigations have tended of late 

 to emphasise the Angiosperm characters of the 

 Gnetales, and MM. Lignier and Tison even reach the 

 conclusion that the innermost envelope of the female 

 flower in Gnetum and Ephedra, and of both flowers 

 in Welwitschia, is a plurilocular ovary containing a 

 single naked ovule. They derive their evidence partly 

 from the anatomical structure of the envelope, partly 

 from its form, terminating as it does in "a long style 

 and a stigma." The anatomical evidence they adduce 

 is discussed in detail, and it is shown that the apparent 

 traces of a vascular system do not necessarily prove 

 the envelope to be an ovary, as well-developed vascular 

 systems are present in the ovular integuments of 

 Cycads and a number of the lower Angiosperms. Re- 

 garding the resemblance of the envelope to a carpel 

 with style and stigma, it is pointed out that, external 

 appearances to the contrary, there is no evidence that 

 it is a reduced form of a functional stigma. Its pre- 

 sent function is to facilitate the dispersal of pollen 

 by attracting insects, and there is no sufficient reason 

 for supposing that it has ever been concerned in the 

 collection of pollen. The question of the cauline or 

 foliar nature of the Gnetalean ovwUe arises in this 

 connection ; this is discussed in detail, and it is shown 

 that recent investigations tend to confirm the opinion 

 that it is cauline. Finally, the new knowledge 

 furnished by MM. Lignier and Tison for Gnetum is 

 summarised, and their comparisons of the Gnetalean 

 and Angiosperm flowers are reduced to tabular form 

 and correlated with those of other investigators, figures 

 being given to render the comparison and correlation 

 clear.— P. A. v. d. Bijl : Heart rot of Ptaeroxylon utile 

 (sneezewood) caused bv Forties rimosus, Berk. 



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The Bearings of Modern Psychology on Educational 

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Color and its Applications. By M. Luckiesh. 

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CONTENTS. PAOF 



Neurology. By Dr. Robert Armsttong-Jones . . . 497 



Psychology 498 



The Declining Birth-rate. By Prof. R. T. Hewlett . 498 



Sang's Seven-place Logarithms. By P. A. M. . . 499 



Our Bookshelf 499 



Letters to the Editor: — 



A Peculiar Thunderclap. — ^John Don 500 



The (jun-firing on the Western Front — Spencer 

 Pickering, F.R.S. ; I. W. Boothroyd . .500 



The Presidency of the Board of Education , . . 501 



Experiments in Aerodynamics. By E. F. R. . . . 501 



Geoffrey Watkins Smith 502 



Notes ■. . 503 



Our Astronomical Column :— 



A Large Solar Prominence 507 



The Spectroscopic Binary tr Aquilae 507 



Banded Spectra from the Electric Furnace 507 



The Work of the National Physical Laboratory 



during the Year 1915-16 . . 507 



The Recent Development of German Agriculture 508 



The Royal Aircraft Factory Inquiry 509 



Lord Kelvin and Terrestrial Magnetism. {IVith 



Dtasrams.) By Dr. C. Chree, F.R.S 509 



University and Educational Intelligence 513 



Societies and Academies . . 514 



Books Received 516 



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