NATURE 



[May 



1913 



ties ol nutrition, absorption, elaboration or chemi- 

 cal metamorphosis, assimilation, elimination, 

 growth, development, functional differentiation, 

 organisation, inanition and disease are shown b\ 

 osmotic growths exactly as by living organisms." 

 Striking examples of a comparatively high degree 

 of organisation are given in the chapter on "mor- 

 phogeny," such, for instance, as the capsular 

 terminations of the filament-like growths obtained 

 with manganese salts, or the "osmotic fungi" 

 which very closely resemble natural fungi in their 

 appearance and structure. One of the most inter- 

 esting features of these growths is the selective 

 distribution of colour in the different parts, one 

 portion of which may be, for instance, greenish- 

 white, another light green, another part dark green 

 and other parts golden yellow. 



Phototropism, galvanotropism, &c. — Prof. Leduc 

 contends that the majority of such phenomena as 

 phototropism, chemotropism and galvanotropism, 

 « hich have been regarded as essentially vital 

 phenomena, can be artificially reproduced with 

 purely mineral or unorganised material. If, fo 

 example, a bath of a salt solution is placed so 

 that one half is illuminated and the other half 



Fig. 3. 



is in darkness, and a drop of water tinted with 

 Indian ink is added, "the particles of carbon 

 abandon the illuminated portion and take refuge 

 in the dark part." These and similar results are 

 utilised by Prof. Leduc in a discussion of the 

 nature of the changes occurring in the production 

 of sense impressions. One of the most striking 

 phenomena in this domain, the deformation of the 

 ovule, with the production of a protuberance on 

 the side of the spermatozoid, which Sachs called 

 "the most surprising phenomenon in fecundation," 

 Prof. Leduc claims to have reproduced artificially 

 in a very simple way : If near an artificial cell 

 (hypotonic), produced in a non-saturated solution 

 of potassium nitrate, a small crystal of potassium 

 nitrate be placed, not only is the artificial cell 

 deformed with a protuberance on the side of the 

 crystal, but the lines of circulation within the cell 

 are evidently also influenced. 



In this small treatise 118 photographs are re- 

 produced, each of which is said "to be expressive 

 of a fact and to represent the result of a series 

 of experiments." It has here been possible only 

 to outline in the most general manner the character 

 and scope of the work. W. A. D. 



NO. 2272, VOL. 91] 



SEMI-CENTENNIAL CELEBRATION OF 

 THE NATIONAL ACADEMY OF SCIENCES 



IN WASHINGTON. 

 THE National Academy of Sciences of the 

 ■*■ L'nited States celebrated the fiftieth anni- 

 versary of its foundation on April 22-24 at 

 Washington. A special programme was arranged, 

 and many distinguished guests were invited to 

 participate in the celebration. In recognition of 

 the function of the academy as the scientific 

 adviser of the Government, President Wilson, 

 Vice-President Marshall, and Chief Justice White 

 took part in the exercises. 



The celebration was held at the Smithsonian 

 Institution, and began on the morning of April 22 

 with an address by the retiring president of the 

 Academy, Dr. Ira Remsen, who reviewed the 

 history of the organisation and gave an account 

 of the scientific labours of the incorporators, and 

 of the various trust funds of the academv. 



Dr. Remsen was followed by President Hadley, 

 of Yale University, whose theme was the relation 

 of science to higher education in America. An 

 address was then delivered by Dr. Arthur 

 Schuster, F.R.S., on international cooperation in 

 research. After a luncheon the academy and 

 guests listened to a brilliant lecture by Dr. G. E. 

 Hale, director of the Mount Wilson Solar 

 Observatory, on the earth and sun as magnets. 

 The lecture was illustrated by lantern-slides and 

 experiments. In the evening a reception was 

 g-iven by the regents and secretary of the Smith- 

 sonian Institution, the hosts being Vice-President 

 Marshall and Chief Justice White, Chancellor of 

 the institution. 



On the morning of April 23 an address was 

 delivered by Dr. J. C. Kapteyn, director of the 

 astronomical laboratory of the University of 

 Groningen, on the structure of the universe. In 

 the afternoon the academy and guests assembled 

 at the White House, where certain medals and 

 prizes of the academy were presented by President 

 Wilson. Dr. R. S. Woodward, director of the 

 Carnegie Institution of Washington, read the 

 reports of the committee on the awards, after 

 which the President handed the medals and prizes 

 to those who were to receive them, or to their 

 representatives, prefacing his action by brief re- 

 marks in which he gracefully referred to the 

 academy as a great society, and as one long 

 associated in an advisory capacity with the Govern- 

 ment of the United States. The awards were as 

 follows : — 



The Watson medal to Dr. J. C. Kapteyn in 

 recognition of his bold, penetrating researches on 

 the problem of the structure of the stellar universe. 

 Dr. Kapteyn received the medal in person. 



The Henry Draper medal to M. Henri 

 Deslandres, of Meudon, France, for his noteworthy 

 researches in astrophysics. M. Deslandres not 

 being- present, the medal was delivered to the 

 French Ambassador, M. Jusserand. 



The Agassiz medal to Dr. Johan Hjort, of 

 Rergen, Norway, for his meritorious contributions 



