110 Thirty-fifth Annual Meeting 
the use of a siphon. In order to have the same volume of the 
mixture flowing constantly a floating siphon was used, so that 
the same head was maintained while the mixture was being si- 
phoned off. The first test made was with an appheation of 1 part 
to 3,000,000. A few trout in the ditch were killed by this solu- 
tion, and some of those in the ponds supplied with water from 
the ditch gave signs of uneasiness. With a mixture of 1 part 
to 4,000,090 there has been no loss of fish. This does not prove 
that the solution can be constantly apphed in flowing water in 
the proportions above given, and what proves to be a proper 
remedy in this particular instance might be fatal to fish if ap- 
plied in some other water system under apparently similar con- 
ditions. 
In considering the eradication of algae in water supplies to 
trout hatcheries and ponds, and especially in connection with 
intensive pond culture, it must be kept in mind that Nature’s 
balance as to water aeration may be upset if the algae is removed. 
* An instance is reported at Cold Spring Harbor, New York, 
where a spring at the edge of a reservoir pond shows a deficit in 
oxygen of 1.25, while in the middle of the pond there is an 
excess of 3.11 in oxygen due to the thick growth of algae, chief- 
ly Spirogyra, which lines the bottom of the pond throughout its 
entire extent, but is heaviest at the middle. 
GROWTH OF EGGS DURING THE PERIOD OF INCUBATION. 
Observations made at various stations indicate that fish eggs 
of almost all species propagated increase in*size from the time 
they are water-hardened up to the time they are about to hatch. 
The amount of increase is not large but will run from about 
one to three per cent., according to the species. This suggests 
that it is unsafe to use the same measure for green eggs and those 
fully developed, especially when large lots are being handled. 
In this connection attention is called to a new form of measur- 
ing gauge to ascertain the correct diameter of fish eggs, devised 
by H. von Bayer, architect and engineer of the Bureau of Fish- 
eries, a sample of which is presented for your inspection at this 
time. A scale of this character is very useful in making tests as 

*M. C. Marsh: Tenth Annual Report of the New York Forest, Fish 
and Game Commission. 
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