96 PROGRESS OF MICROSCOPICAL SCIENCE. 
Bacteria of Denmark.—A Danish naturalist, Dr. Eug. Warming, 
has been devoting himself to this subject, and has published a paper, 
which is given in an abstract of some length in the ‘ Journal of 
Botany’ (December 1876). We can, however, only find space for a 
portion of this notice. It seems that all along the Danish coast there 
is found, during calm weather in the summer months, a red coloration 
of the water close to the shore. The cause of this singular phe- 
nomenon is referred to Bacterioid masses which cling to Zostera and 
seaweeds, and, as might be expected, lose their hold when a storm or 
a high tide supervenes, and do not regain their position and appear in 
sufficient quantity to colour the water until calm has been restored. 
The wet weather of autumn also breaks up the masses, but during the 
whole winter it is possible to find plants covered with Bacteria 
capable of ready revival, even if their habitat be frozen over. Pro- 
fessor Warming has made a study of this subject with his usual care 
and success, the results of which—the discovery of several new 
specific and varietal forms, and the broaching of theories as to struc- 
ture, reproduction, and classification—are noticed in a brief manner. 
Sometimes floating masses composed of Clathrocystis roseo-persicina 
oceur, but most Bacterioid life is found below the surface; here, 
when decomposition has only slightly advanced, one sees principally 
small individuals of Monas vinosa, but at further stages many other 
red-coloured forms as well as various colourless ones are developed. 
A common species is Monas Okenii, of which the Danish examples are 
not so deeply coloured as are those figured by Cohn ; marine specimens 
are oval or cylindric and straight, fresh-water ones somewhat spiral 
in form ; smaller individuals have a single posterior cilium, the larger 
one at each end. As to division, Professor Warming believes that 
only the small ones exhibit it ; occasionally very long cells were found, 
but they were not constricted in the middle, and showed no sign of 
division. This does not appear to exhibit a “ zooglea” state. ‘Then 
follow various other species, till we come to Bacterium sulphuratum, 
under which name are united a number of forms, which together 
make up the chief part of the red coloration. The states in which 
this appears are:—1. As spheres (Monas vinosa, Ehrbg). 2. As 
roundish bodies, usually with a constriction and with granules 
grouped at the ends (Monas Warmingii, Cohn). 3. Like Monas vinosa, 
but crowded with sulphur-grains (Monas erubescens, Ehrbg.). 4. Long, 
narrow, cylindrical, and filled with sulphur-grains (Ahabdomonas 
rosea, Cohn). Finally, the series is brought to a close by a spiral 
form, the amount of torsion varying from scarcely anything to more 
than one complete turn. Professor Warming is at a loss to know 
what becomes of the large forms ; he thinks it possible that they form 
a sort of spore like Ascococcus. He then describes various other 
species, which are pretty fully given by the ‘ Journal of Botany,’ 
which concludes as follows :—Professor Warming did not succeed in 
directly making out the cell-membrane; in the true Bacteria he has 
never seen the plasma shrink from the cell-membrane by the action of 
reagents, neither has he observed any internal molecular or granular 
movement. Sometimes, however, vacuoles are formed round the 
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