800 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [6] 



with scrupulous care would iusure success, as far as the danger from 

 fungus is concerned, in conducting this mode of retarding development. 



The second series of experiments were conducted at Washington, in 

 association with Col. M. McDonald, this gentleman having kindly 

 undertaken to aid in the work of experimentation, by means of various 

 ingenious forms of small and convenient hatching apparatus of his own 

 devising, mostly made of glass. The method pursued consisted partly 

 in treating the eggs for some time on the dry principle on trays, com- 

 pleting the incubation afterwards in the glass apparatus fed with water 

 from a coil of tin pipe kept under ice in a refrigerator. This enabled us 

 to maintain the temperature of the water supply at a pretty constant 

 point, rangmg from 60° to 63° F. It was necessary, on account of the 

 distance which the eggs bad to be transported, to use trays covered 

 with damp cloths, on which the impregnated, water-swollen ova were 

 carried in transit from the spawning grounds. The experiments were 

 conducted in the basement of the Smithsonian Institution, where some 

 of the trays of eggs were placed in a refrigerator and others put directly 

 into the water at the temperature stated above, using the McDonald 

 apparatus. The results of these experiments were of great interest and 

 of considerable value, as giving us data for certain precautions to be 

 observed in the conduct of future work and experimentation, as may be 

 learned from the account of them which follows. 



Colonel McDonald found it necessary to devise some ready means of 

 transporting the ova from the spawning grounds over a score of miles 

 down the Potomac. This necessity for an expedient proved that the 

 transportation of ova by the dry method immediately after they had 

 been water-swollen was possible, and that it would answer for long dis- 

 tances. To illustrate : some were kept on the trays in good condition 

 for seventeen hours, in the ordinary temperature of the air, 70° to 80° 

 F., prevailing at that season of the year (July). When the temperature 

 of the air was up to 90° F. it was found that the ova carried on trays 

 and allowed to remain on them would tend to si)oil quickly, as Bacteria 

 ^ndVibriones were distinguishable on all the spoiled putrescent ova care- 

 fully examined under the microscope. It is therefore evident that in 

 warm weather, in transporting ova by the dry method for long dis- 

 tances, it would be necessary to take certain precautious to prevent the 

 access of the germs of such putrefactive organisms to the eggs. Essen- 

 tially the same method of procedure recommended to guard against the 

 introduction of the spores of the saprolegnious fungus to the eggs would 

 apply here. Such precautions, however, would only be necessary where 

 it Avias desired to retard the development for a long time, in case it was 

 desired to transport the ova long distances. I think it would be found 

 practicable to carry eggs on trays on damp cloths for ai)eriod of twenty- 

 four to forty-eight hours without the least difSculty, x)rovided a refrig- 

 erating apparatus was constructed in which the temperature could be 

 kept at 60° to 65^ F. j below this temperature it would not be safe to go 



