498 RECORD OF CURRENT RESEARCHES RELATING TO 



in, and all floating grains stirred down. Then by a circling movement 

 of tlie hand the foraminifers will be got to the top, and by gradually 

 tijjping the saucer and slowing up the movement they can be worked 

 to one edge of the little pile of sand, and thence carefully dipped up 

 with a rubber bulb pipette. In this way they are got almost pure. 

 Only a little sand must be washed at a time, or not all the foraminifers 

 will be got out, and very little water must be used or sand will get 

 mixed with them. Much water moves the light sand, but a shallow 

 wave seems not to stir it, but yet rolls the shells along. 



Continuous Measurement of the Intensity of Daylight, and its 

 Application to Botanical Researches.* — M. Kreusler describes an 

 instrument whereby the intensity of daylight can be estimated for any 

 hour ; it consists of a hollow drum in which is cut a slit imrallel to 

 the terrestrial axis ; behind this slit is a strip of sensitized paper, 

 across whose surface the slit is caused to pass by means of clockwork. 

 To be able to compare the shades of colour, several tints are produced 

 also on sensitized paper, by causing the direct rays of the sun to fall 

 on the paper at various angles for twenty seconds, this being the length 

 of exposure for each part of the registering paper. An inclination of 

 60° produces half tint, &c., the tints being numbered 1, 2, 3-10, 10 

 representing full sunshine. 



In the second portion of his paper the author states that bright- 

 ness of light is accompanied by increased assimilation on the part of 

 the plant ; but this regularity of increase continues only up to the 

 point when the intensity of light is one-eighth that of the full sun- 

 shine, and after that assimilation goes on less rajjidly, not keeping 

 pace with the increased intensity. Now, as increased intensity of 

 light is accompanied by increased chemical intensity, the former may 

 be used as an indicator of the latter, as regards plant physiology, as it 

 was found that assimilation increased as chemical intensity increased, 

 at first rapidly, but afterwards in a less degree. Sub-aquatic plants 

 are not of value in determining assimilation, as they are not sensitive 

 enough to small changes of light ; an apparatus has therefore been 

 devised in which it is possible to expose whole plants to the light, and 

 is on the principle of an aspii'ator. 



Collecting Marine Diatomaceae.t— According to Mr. K. M. Cun- 

 ningham, a quick way of getting marine forms of Diatomacese is to take a 

 peck of fresh oyster-shells, and brush the back of each one into a basin 

 of water ; some cotton should be cut up into tufts and immersed in the 

 fluid, which will make the product suitable to be dried and ignited, as 

 it will take fire at a red-heat and entirely burn ; it will, however, 

 take a stronger heat to destroy the particles of animal matter of the 

 oyster — the young spawn which will naturally be brushed into the 

 water. This oyster-shell process will give Pleurosigma and Coscino- 

 discus in abundance. 



* ' Bied. Ccutr.,' 1879, p. 117; see 'Journ. Cliera. Soc.,' Abstr., xxxviii. 

 (1880) p. 188. 



t ' Am. M. Mior. Jouru.,' i. (1880) p. 66. 



