1897.] NEAV YORK ACADEMY OF SCIENCES. 381 



same method has since been employed by Kofoid* with success 

 in his shallow fresh-water collections, and is recommended by 

 Professor Joh. Frenzelf as an effective method, but we believe 

 that for the small quantit}^ of water necessary for quantitative 

 anal3'sis by the Sedgwick-Rafter method| as here employed, or 

 for the " planktonocrit,''§ the above described apparatus is ade- 

 quate and accurate for collections up to at least 300 metres in 

 depth. To a litre of the water thus obtained is then added 20c. c. 

 of commercial formalin, by which the organisms are killed ; after 

 which the whole amount is filtered and then preserved in 20c. c. 

 of a 5 % solution of formalin. Counting is then possible accord- 

 ing to the original Sedgwick-Rafter plan. 



In order to illustrate the distribution discovered through this 

 vertical in Puget Sound, five representative subjects, both plant, 

 animal and inorganic, were chosen from the data observed, and 

 these have been recorded by the plotting shown in Plate II. of 

 this paper. The most varied of these subjects are the diatoms, 

 which have been somewhat grouped together in this discussion, in 

 so far as the}^ generally agree in form and follow the same plan 

 of distribution. Thus, under the generic title Coscinodiscus have 

 been included in the plotting three species typified by C occulus 

 iridus, while the larger sized forms of the same general 

 shape have been arranged under Coscinodiscus asteromphalus 

 and include a few of the genus Arachnodiscus, and some indi- 

 viduals of Aulacodiscus. This plan seems advisable, since, with 

 the low magnification used in counting, it is difficult to separate 

 the constituent parts with certainty, and they all show uniformity 

 throughout, which would tend to group them together in any 

 synthetic treatment. Under the genus Feridinium also are 

 given two species. 



There are thus laid down on Plate II. five horizontal lines in- 

 dicating the five levels from which material was secured, and on 

 these lines were laid off distances corresponding to the numbers 

 of individuals of each group obtained by us ; the points were then 

 connected by lines and the enclosed areas shaded in black to indi- 

 cate the living and unmutilated condition of the organisms, and 

 by oblique-lined areas to show the certainly lifeless or fragmented 

 individuals of the same forms. The width of the black columns, 

 therefore, at any of the observed levels, indicates the proportion- 

 ate abundance of the unmutilated individuals at that point, as 

 likewise the width of the oblique-lined belt shows the quantity of 

 the dead and the broken tests of the same. 



* Bulletin of Illinois State Lab. Nat. Hist., Vol. V., Art. I. 

 + Biologisc'hes Centralblatt, XVIL, Bd. Nr. 5, p. 190. 



i See Kofoid, ibid., p. 21, also Jackson and Whipple in Technology Quarterly, Vol 

 IX., No. 4, 1896. 



i By C. S. Dolley, Proc. Acad. Nat. Sci., Philadelphia, May, 189G. 



