90 



NATURE 



[March i8, 1920 



means of a new apparatus designed by Dr. F. F. 

 Blackman for measuring a small output of oxygen 

 in photo-synthesis. The leaf is illuminated in a 

 closed circuit in an atmosphere of hydrogen and 

 carbon dioxide. In part of the circuit gases are 

 carried over palladium black, so that oxygen pro- 

 duced unites with two volumes of hydrogen. The 

 threefold reduction of volume resulting is measured 

 by a gas burette in the circuit. In this apparatus 

 oxygen pressure is kept so low that no further 

 development of chlorophyll takes place, while photo- 

 synthetic production of oxygen can be measured with 

 great accuracy. If a leaf is cut from a seedling 

 growing in the dark at an early stage of development, 

 and then partially greened by exposure to light in 

 air, its photo-synthetic activity when transferred to 

 the apparatus will be very small or nothing. If 

 exactly the same procedure is repeated a few days 

 later, the photo-synthetic activity may be nearly as 

 great as in the normallv develooed leaf. — Dr. B. 

 Moore, E. Whitley, and T. A. Webster: Sunlight and 

 the life of the sea. [Studies of the photo-synthesis in 

 marine algag. (i) Fixation of carbon and nitrogen 

 from inorganic sources in sea-water; (2) increase of 

 alkalinity of sea-water as a result of photo-synthesis 

 and as a measure of that process ; and (3) relative 

 photo-synthetic activity of green, brown, and red sea- 

 weeds in light of varying intensity.] The vernal out- 

 burst of green life which occurs at the spring equinox 

 is occasioned by the rapid change in intensitv of dailv 

 illumination. A study of the seasonal variations in 

 plankton around Port Erin, Isle of Man, has now 

 been carried on for many years by Prof. W. A. Herd- 

 man and his co-workers. In many years the great 

 outburst of diatoms occurs before the temperature of 

 the water has even begun to move from its winter 

 level. It thus becomes clear that it is the longer, 

 brighter day, with increased altitude of the sun, which 

 is the primary factor in the sudden dawn of the life 

 of the sea each spring. This is illustrated by a chart 

 upon which are shown for each month (i) temperature 

 of the sea, (2) number of diatoms, (3) hours of bright 

 sunshine, (4) total radiant energy, and (5) the amounts 

 of nitrogen peroxide present in the air (formerly called 

 "ozone of the air" or "active oxygen "), as taken at 

 Radcliffe Observatory, Oxford, by Schonbein's 

 "Ozone" papers. A sudden rise in radiant energs' 

 in March is accompanied by (i) the diatomic outburst 

 and (2) increased nitrite content. It has been shown 

 that the growing diatoms capture this enormous in- 

 crease of light, and utilise it for building both carbon 

 and nitrogen into their organic substances. The 

 source of the nitrogen is the atmospheric elemental 

 nitrogen dissolved in the sea-water, and not ammonia, 

 nitrites, or nitrates. The source of the carbon is the 

 carbon dioxide of the bicarbonates of calcium and 

 magnesium dissolved in sea-water. As this carbon 

 is removed in photo-synthesis the sea becomes always 

 more alkaline, and the change of reaction can be used 

 as a rough measure of the marine crop. Although the 

 increase of alkalinity is small, yet the volume of sea- 

 water is so immense that, as has been pointed out 

 by Moore, Prideaux, and George Herdman, suppos- 

 ing this to happen to a depth of 100 metres over the 

 surface of the sea, then the crop of moist plankton 

 per square kilometre would amount to about i,_i;oo,ooo 

 kilograms. This corresponds roughly to about 10 tons 

 per acre. 



Royal Microscopical Society, February 18.— Prof. John 

 Eyre, president, in the chair. — Dr. Agnes Arber : 

 (i) Studies on the binucleate phase in the plant-cell. 

 Rudolf Beer and Dr. Agnes Arber : (2) Multinucleate 

 cells : an historical study (1879-1919). These two 

 papers were read as one. It was pointed out that in 

 NO. 2629, VOL. 105] 



1844 Nageli first stated that the plant-cell is essen- 

 tially uninucleate. Those botanists who have from 

 time to time directed attention to exceptions to 

 Nageli 's rule, usually attributed little importance to 

 them, but recent work has made it clear that a bi- 

 nucleate or multinucleate condition is a very constant 

 character of young and active tissues. The authors' 

 observations on the subject were then discussed, the 

 case of the nuclei of the young inflorescence axis of 

 Eremurus himalaictis being described in detail. It was 

 shown that the binucleate condition arises by mitosis. 

 The division is normal up to the formation of the 

 daughter-nuclei and the initiation of the cell-plate. 

 At this point the mechanism apparently breaks down, 

 the cell-plate is resorbed, and the spindle-fibres and 

 associated cytoplasm — the " phragmoplast " of Errera 1 



^become transformed into a hollow sphere which | 



encloses the two daughter-nuclei, and eventually, by 

 gradual expansion, merges with the cytoplasm lining 

 the cell-wall. For this hollow shell, derived from the 

 phragmoplast, the authors have proposed the term 

 " phragmosphere " (Proc. Roy. Soc, B, vol. xci., 

 1919, p. 10). The question as to how the binucleate 

 condition of these young cells passes into the uni- 

 nucleate condition characteristic of mature tissues, 

 was then considered. It was shown that, although 

 bilobed nuclei often occur, which at first sight suggest 

 that the two nuclei have fused together, more critical 

 examination indicates that these nuclei are single . 

 nuclei, the lobing of which is an indication either of 

 senilitv (axis of Asparagus) or, in some cases, of an 

 effort ' by young and active cells to increase their 

 nuclear surface (stelar parenchvma of roots of 

 Stratiotes, leaf epidermis' of Hemerocallis). The 

 authors think it niore probable that the uninucleate 

 condition is restored by degeneration and resorption 

 of one nucleus, than by the fusion of the two nuclei. 

 The paper closed with a brief reference to the signi- 

 ficance of the multinucleate phase. 



Manchester. 



Literary and Philosophical Society, February 3. — Sir 

 Henry A. Miers, president, in the chair. — Prof. E. 

 Knecht : Alpine insolation effects on unprotected wood. 

 Effect of direct sunshine on the wood of Alpine 

 chalets. When exposed for about a hundred years 

 the surface of the wood was sometimes charred or 

 scorched to a uniform black, presenting under the 

 microscope the appearance of coal. The changes were 

 probably brought about more by thermo-chemical than 

 by photo-chemical action. By prolonged heating of 

 wood to 93° C. the author had produced incipient 

 blackening of the surface. The temperature of de- 

 composition of wood appeared to have an important 

 bearing on the question of coal-formation. — W. 

 Thomson and H. S. Newman : The behaviour of 

 amalgamated aluminium and aluminium wire. In- 

 vestigations on the fine feathery growths produced 

 when aluminium wire is brought into contact with 

 mercury. No such growths are obtained from amal- 

 gamated magnesium, although it undergoes oxidation 

 more readilv than aluminium at the ordinary tem- 

 peratures of the air.— C. E. Stromeyer : The after- 

 effects of cannibalism. Cannibalism would not be 

 indulged in by people with vegetarian tastes, or bv 

 those who, having a craving for animal food, 

 could satisfy it. Others who had this craving, 

 but no animals to eat, would become cannibals. 

 No State in which indiscriminate man-eating was 

 indulged in could have flourished. Officials were there- 

 fore appointed who invented rites which became 

 religious ceremonies. Human sacrifices were, to a 

 certain extent, discontinued, but the rites were con- 



