110 TYPICAL QUEENSLAND LAGOON 
of the pipes. It is found in active growth and decay nearly 
all the year round, but about the autumn decay is usually 
more marked, whilst is is less noticeable in the winter. The 
growth extends at times for about 5 inches from the iron 
to which it is attached, forming a dense mat in the lower 
2 inches. Statoblasts are found in the Plumatella all the year 
round, but are most plentiful when the decay is most marked. 
Freshwater sponge and Hydra are always found associated 
with the Plumatella. The smell from this Bryozoa and Sponge 
when in process of decay is most offensive, and is a serious 
cause of odour in the water when it is passed through iron 
pipes. I might here remark that these organisms will not 
grow in the water which is produced in the methods about 
to be described. (Appendices VI. and XII.) 
I find it difficult, in fact almost impossible to describe 
satisfactorily the odour of this water; it may be described 
in a vague manner as a mixture of Vegetable—Salt Marshy— 
Grassy and Fishy—each item predominating at different times 
of the year. During long periods of drought the odour is 
almost absent, and it is I think most offensive when it has 
been in contact with decaying Plumatella. 
As regards chemical compostion I find the water of this 
lagoon to be comparatively constant throughout the year, 
a list which I have prepared giving the monthly averages of 
weekly analyses of samples drawn 5 feet below the surface 
since May, 1904, shows the organic matter as indicated by 
Albuminoid Ammonia determination, to have been highest 
in March, when it was averaged .367 parts per million for 
the month, the lowest figure obtained being for January, 
when it averaged.260 p.p.m. Nitrates were absent through- 
out the year, whilst Nitrites were only occasionally searched 
for, but never found present. (Appendix VII.) 
In colour the samples varied considerably, the highest 
figures being obtained in May and June during the period of 
of vertical circulation in the lagoon, the variation being from 
52 on the platinum scale in June, 1904, to 20 on the same scale 
in January, 1905. The Chlorine figure was practically 
constant throughout the year, being about 34 parts per million 
or roughly 2.4 grains per gallon. The hardness of this water 
is very low, being about 3 degrees on Clarke’s scale. 
