54. Thirty-Third Annual Meeting 
of water, which was aerated with a dipper every quarter of an 
hour. The temperature of the water was kept between 57 de- 
grees F. and 59 degrees F. After five hours twenty-one fry had 
succumbed, the others were showing distress, and the experiment 
was abandoned in order to save the fry. A can painted on the 
inside was carried as a control during this experiment, under 
exactly the same conditions and of its 300 fry only two were dead 
at the end of five hours. 
I think one may confidently say that galvanized iron is dan- 
gerous for brook trout fry and that therefore galvanized iron 
containers unless coated in some way, are to be avoided if the 
fry are to be held long in them. Of course if there is a flow of 
water the poisonous agent will not become concentrated enough 
to do harm, but if the water stands in contact with the metal 
something goes in solution and becomes strong enough after sev- 
eral hours, more or less, to kill brook trout fry and perhaps other 
species. I suppose that it is the zine of the galvanizing process 
which comes off. Various conditions probably may modify the 
toxicity, as for instance different waters would probably dis- 
solve the metal differently, and different galvanizing processes 
may perhaps give different results. 
I imagine that fish culturists in transporting have lost fry 
and possibly larger fish from this cause, perhaps without dis- 
covering the real trouble. Often on short trips no trouble may 
come and no doubt the conditions sometimes permit without 
harm a longer exposure than proved fatal in the few observa- 
tions I have made. Moreover fry may gradually become accus- 
tomed to water containing zinc. Some of the above experiments 
were recently repeated at the St. Louis Exposition and the re- 
sults showed a much less injurious effect for the galvanized iron. 
But the fry used were taken from the water in which zine had 
been slowly accumulating, and analysis showed it had taken up 
appreciable quantities of the zine. 

