QUEKETT MICEOSCOPICAL CLUB. 265 



taking a shilling pocket lens and spending his time on the shore 

 examining anything he could find. He did so, and became an 

 enthusiastic microscopist, although he had previously known 

 nothing about it. Mr. Scourfield said that there was an interesting 

 note of his on the polarising granules in Actinosphaerium. 



Messrs. Watson very kindly sent a quantity of Oamaru earth 

 for distribution, and a member brought a jar of " Palestine wine." 

 The President said that this substance (which is also known as 

 " Californian bees ") is the ginger-beer plant. It is a symbiotic 

 association of a form of yeast and a bacterium, and may be fed 

 on sugar, which it ferments. 



Mr. A. A. C. Eliot Merlin then read a " Note on Photographs of 

 Nitzschia valida and the Process of Auliscus." Two photo, 

 graphs were exhibited and the method of taking them described. 

 The objective used was a l/12th in. apo. of N.A. 14, the con- 

 denser a P. and L. dry apo. at full aperture, and the illuminant 

 the sun's disc reflected by a heliostat. A screen consisting of a 

 solution of methyl green in glycerine and containing a piece of 

 blue glass was used and a tank of water 8 in thick. Exposure, 

 20 seconds on Wratten "M " panchromatic plates. A specimen 

 of N. valida was shown under the microscope. It is an 

 excellent test for medium and high-power objectives, the trans- 

 verse striae being 57,000 to 58,000 per inch, and the longitudinal 

 48,000 to 51,000. Thus the structure is well within the grasp of 

 a lens of 0-65 N.A. Both photographs showed excellent contrast 

 although, owing to their great transparency, both objects were 

 difficult to photograph, especially with a large illuminating cone. 



The Hon. Secretary read a note from Mr, Crowhurst, of 

 Bromley, on a purple bacterium, a species of Lamprocystis. It 

 forms large pink-violet, spongy masses, made up of thousands of 

 bacterial cells united by their gelatinous walls. Mr. Crowhurst 

 very kindly promised to send a supply of Lamprocystis at a later 

 date. Mr. Scourfield said that Mr. Nelson had succeeded in 

 demonstrating the flagellum of the bacterium. The thanks of 

 the meeting were accorded to the foregoing donors and authors. 



The President then called upon Mr. N. E. Brown to read his 

 paper, " Notes on the Structure and Growth of Diatoms." A 

 diatom, said Mr. Brown, is a microscopic aquatic plant having 

 a transparent siliceous shell constructed on the plan of a 

 pill-box. The structure of the valve may usually be classified 



