PROGRESS OF MICROSCOPICAL SCIENCE. 
143 
zine,’ August, and promises a fuller account in tlie 1 K. Yet. Akade- 
mions Ofversigt.’ Tlie notice constitutes part of Professor Norden- 
skiold’s paper. It seems that one of the species of Algse met with on 
the inland ice occurred in such vast quantities, that the surface of the 
ice throughout larger or smaller tracts was tinted with a peculiar 
colour. Two others seemed exclusively to belong to the fine sand, 
which is found either in the form of a thin covering on the surface of 
the ice, or as a more or less thick layer at the bottom of the pipe-like 
holes that appear in the surface. The first-mentioned species, occur- 
ring copiously, does not require any such substratum, but is found 
principally on the sides of ice-hills, where the water from the melting 
ice filtered itself out between the little inequalities of the surface. 
The most copiously represented species has the form of a short thread, 
not spreading out in branches, but consisting of a single row of cells ; 
the number of cells in each thread is 2, 4, 8, or at most 16. Threads 
of 4 and 8 cells are most common. The species very frequently ap- 
pears only as a single cell. The threads are usually a little bent, some- 
times, when the number of cells is 16, forming a complete semicircle. 
The number two or its multiples taken as the standard for the number 
of cells in the separate threads is accounted for by the regular continuous 
bisection of the cells, whereby their propagation proceeds The con- 
nection between the cells is the looser the older the partitions become, 
as the older membranes assume a looser consistence. In a thi'ead of 
16 cells, the connection between the eighth and ninth cells is soon 
broken, and in the two threads thus resulting the connection between 
the fourth and fifth cells is weaker than that between the second and 
third or the sixth and seventh. The threads therefore often lie bent 
at an angle. The diameter of the cells is 0'008 — 0 - 012 mm., and 
their length O’ 016 — 0*040 mm. Individual cells may sometimes 
attain a length of 0 1 065 mm., and a breadth of 0*015 mm., whereas 
a great number of other single cells are met with of very small 
dimensions, from spherical forms of only 0 • 006 mm. diameter to those 
of ordinary form and size. As the ends of the cells, where they are 
joined together, are rounded, there is, of course, a contraction between 
them, which becomes more and more conspicuous as the connection 
between them is loosened by time. The membrane is thin and hya- 
line, and its outermost layer (the remnants of the membranes of the 
mother-cells altered after division) is of an almost slimy consistence, 
whereby the cells are for some time kept together. The contents of 
the cells are in part concealed by a dark purple-brown colouring 
matter, which in dried cells is immediately drawn out on wetting 
them. The centre of the cells is occupied by an oblong or cylin- 
drical mass of chlorophyll, of somewhat irregular contour, in the 
extremity of which two kernel-formed rounded bodies are imbedded, 
which in general cannot be perceived by the eye till the colouring 
matter has been removed by means of reagents. We sometimes 
meet with four such bodies in one cell, sometimes but a single 
one : the former a result of accidentally checked division of the 
cells ; the latter of such division having lately taken place. In 
the liquid of the cells a number of small grains are found, which are 
VOL. VIII. M 
