BY HARDOLPH WASTENEYS. 1c9 
Quantitative estimations of the bacteria in this water 
have been made at irregular intervals since November, 1904. 
As usual with waters of this class the numbers are com- 
paratively small, averaging about 400 per cubic centimeter 
when grown on neutral agar medium. (Appendix V.) 
Sufficient analyses have not been made to show the 
seasonal variations in the different micro-organisms in this 
lagoon water, it is noted, however, that the diatom Synedra, 
and the chlorophyll alga Protococcus are always more plentiful 
after rain. 
Comparatively large areas of a scum consisting for the 
most part of Anaboena, Protococcus and Oscillaria float on the 
surface of the lagoon during the summer months, and are 
found generally near the edges where they have been blown 
by the prevailing wind. The protozoa Peridinium is also 
very plentiful, and is found in large numbers associated 
with the scum before mentioned. 
A micro-organism which I consider to be a variety of 
Protococcus is the predominating organism in this lagoon , 
it may be seen at all times of the year, but particularly in 
summer and after heavy rains, distributed throughout the 
surface as a bright green powder of irregularly shaped 
particles. This organism, which I have not yet been able to 
identify satisfactorily, but specimens of which Mr. Bailey 
has kindly forwarded to Professor Borge, in Germany, for 
determination, is most obnoxious when plentiful; it has 
not yet given trouble in the lagoon under discussion, 
but in a similar and not far distant lagoon it became, some 
months ago, so bad that the water was of a bright green 
colour throughout, and at the edges in some places the organism 
was so plentiful as to impart to the water the consistency 
of mud. The odour given off by this organism was so bad 
that a workman, the nature of whose employment 
required that he reside near the lake, asked for and was 
actually supplied with a considerable quantity of disinfectant 
for use around his residence whilst the lake was being emptied. 
Spirogyra grows abundantly during the summer in the 
shallow water round the edges of the lake. 
When this lagoon water is passed through iron pipes 
under low pressure, abundant growths of the Bryozoa, 
Plumatella soon become attached to the interior surface 
