THE STURGEONS AND STURGEON INDUSTRIES. 
275 
some practical method was devised of overcomiug losses from this cause it would be 
of little use to attempt to do much iu the artificial propagation of this fish. In the 
course of about five days the eggs, which were placed on the cheese-cloth bottoms of 
the floating hatching boxes, which I had arranged in the large fresh-water pool con- 
nected with the eastern end of the Chesapeake and Delaware Canal, were for the 
most part attacked so as to be beyond the possibility of rescue. Not more than about 
5 per cent, of the whole number were by that time free from the parasitic fungus, so 
that those which survived to hatch on the sixth day were very few in number. 
A serious difficulty was also encountered in the firmness with which the affected 
eggs adhered to the cheese-cloth and to the good ones, so that it was found to be very 
hard to remove the damaged ova without injury to the good ones iu attempting to 
thus prevent the spread of the scourge. In consideration of this circumstance the 
only practicable remedy seems to be prevention; that is, the germs of the fungus 
must be removed from the water used in treating the ova when they are fertilized and 
iu hatching them. Or, the water used in fertilizing and hatching the eggs must be 
sterilized. Of these two methods the first seems to be the simplest and easiest of 
application, since the spores of the Saprolegnia are comparatively large, so that they 
may be removed from the water by a system of filtration. 
If a system of cotton- wool filters were attached to the supply from the pumps in 
such a way that the water could be continuously forced through one of a series of 
filters, while others of the system were being cleaned and renewed, it would probably 
be possible to get the water used iu the hatching operations free from the noxious 
spores or germs of the fungus. This plan would not involve the expenditure of any 
additional steam-power and but little additional labor and expense. The hatching 
troughs, with their trays of eggs, would of course have to be provided with tight- 
fitting covers to exclude the dust and possible contamination from the air. 
Another more expensive but perhaps more tborougli method would be the sterili- 
zation of the water used iu the hatching operations. This could only be accomplished 
by means of heat, supplied by the superheated steam from the boilers of the pumping- 
engines conveyed into a closed iron chamber with an outlet for the condensed steam. 
Through a coil of pipe placed iu this heating chamber, the water used iu the hatching 
operations would be forced and heated up to a point iu its passage through the coil at 
which the germs of the fungus would be killed. The heated water for hatching would 
then have to be passed through a second coil, submerged in the cold running water of 
the river, to again lower its temperature to that of the water before heating, after 
which it would be safe to let it flow over the eggs. The water if heated iu this way, 
however, might be so deprived of air which it had contained, that it would be necessary 
to aerate it. This could probably be done by allowing it to flow under pressure from 
fine nozzels in a fine spray, so as to carry air into the water in the tanks, the nozzles 
being so disposed as to have their outlets elevated several inches above the surface of 
the water, iu the same manner as the water is aerated for the aquaria at the Central 
Station of tbe U. S. Fish Commission at Washington, and in the hatching rooms in the 
laboratory buildings at Woods Holl, Mass. 
Another method which suggests itself, is to force the water for purposes of sterili- 
zation through a coil of copper pipe, suspended over a furnace grate arranged some- 
what after the manner of a Herreshoft' steam coil-boiler, then conveying the water 
through a second coil submerged in running water at the ordinary temperatue, and then 
