摘要: A simply made, cheap chamber for counting nannoplankton is described with detailed instructions maintcnancc, use, and testing its accuracy. If certain precautions are taken the results of counts made therein distributed according to Poisson series. The itself a rectangular tube. inverted microscope technique developed by Utermshl (1931a, :1931b, 1936; Lund, Kipling, Le Cren 1958) suitable large small algae, but if both arc be enumerated very expensive necessary. In my view most chambers haematocytometer, Sedgwick-Rafter, or Kolkwitz type (for review methods estimating algal numbers see Lund Talling 1957), which can used on an ordinary microscope, unsatisfactory, chiefly because algae not sedimented at random high-dry immersion objectives cannot used. case importance distribution much greater than larger bccausc otherwise, then whole floor has examined. This serious matter when low powers magnification count relatively objects, high ones minute time involved becomes large, all these considerable area. Then disadvantage size populations counting, so often cited, indeed true. further that they must machine-made dcgrce precision; this true also recently Palmer-Maloney (1954) slide. 1 My grateful thanks due Miss C. Kipling carrying out statistical analysis, Mr. II. Gilson who suggested using dial gauge, V. G. Collins J. Soak in haematocytomcter test p. 63. present chamber, tube, ease anyone cost glass cutter, slide, one two long coverglasses, little cement. dozen could easily day it does some have bc rejected become broken. exact depth critical, though is, course, essential any cvcn throughout working length. within random, lenses magnifying forty fifty times Much deeper chambers, examination under low-power lenses, equal ease, probably use highpower material thinner coverglasses sides: such would unsuitable might well satisfactory bacteria. Jf form there obviously no difficulty making bacterial counts, roofing coverglass now chamber. killed Lugol’s solution, without addition acetic acid, cells will soon come rest bottom disturbed therefrom. Dr. McArthur kindly tested finds revolutionary (1934, 1947a, 1947b), means possible make anywhere world, land, sea, air. This, preliminary concentration sample scdimentation.